Guppy Diseases, Parasites & Remedies

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Unfortunately, there are many diseases and parasites that can harm your guppy fish. The good news is that many of them can be cured. In this article, I will try to present to you the most common guppy diseases and infections, prevention, and remedies.

Important: it is easier to prevent diseases than to treat sick fish!

The most common guppy fish diseases such as ick (white spot), velvet (gold dust), fin rot and flukes can be cured with the Seachem ParaGuard from medication.

Here are some very basic steps to prevent most of the diseases:

  • Keep water parameters and temperature at required levels
  • Feed your fish well, but do not exaggerate
  • Maintain your tank regularly, perform weekly partial water changes
  • Remove any dead fish immediately from your tank
  • Inspect your fish visually on a daily basis
  • Remove any sick fish from your main tank and place it into a hospital tank
  • Before introducing new fish to your main display tank, keep them in a quarantine tank for 3-4 weeks

For more information about guppies please read my guppy fish care guide, where I share my experience of more than 15 years of keeping guppies.

Stress as a Precursor

Stress is a primary culprit behind most diseases afflicting guppy fish. When stressed, their immune systems weaken, making them more susceptible to infections and parasites.

Several factors can induce stress. In their natural environment, guppies are nestled amidst plants, tree roots, branches, and other natural hideaways.

To alleviate stress, ensure your tank mimics this natural environment. Live aquarium plants, in particular, make excellent hiding spots.

Overcrowding is another significant stressor.

While guppies are peaceful by nature, housing them with more aggressive species like bettas, gouramis, angelfish, or barb fish can lead to distress.

Temperature fluctuations, whether too low or excessively high, further stress guppies. It’s advisable to use a heater to maintain a stable water temperature.

Lastly, water quality plays a pivotal role not only in stress but also in disease onset. Regularly perform partial water changes (30-50%) each week. Ensure the new water matches the desired pH level, and temperature, and is devoid of chlorine.

Most Common Guppy Illnesses and Diseases

Guppy illnesses can range from external infections like Ich and Velvet to internal ailments such as Dropsy. Recognizing and understanding these common diseases is vital for ensuring the health and longevity of these popular aquarium fish.

Here is a list of the 17 most common guppy diseases:

  • External Diseases
    • White Spots – Ich, Ick
    • Velvet (Oodinium)
    • Fin, Tail Rot
    • Columnaris & Mouth Fungus
    • Gill Flukes, Gill Worms
  • Internal Diseases
    • Guppy Disease (Protozoan)
    • Dropsy
    • Red Blood Spot on Guppy Stomach/Body
    • Camallanus Internal Worm
    • Hexamitiasis – Hole in the Head or Body
  • Physical and Behavioral Anomalies
    • Swollen Gills and Gasping
    • Popped Eyes
    • Swim Bladder Disorder
    • Swim Bladder Inflammation
    • Bent Spine (Scoliosis)
    • Fish Tuberculosis
    • Viral Haemorrhagic Septicaemia (VHS)

Important: in order to raise the chance of curing your guppies you should always keep medication at home for the following most common guppy diseases. 

Now let’s get into details about the common diseases that affect guppies.

White Spots – Ich, Ick

Probably the most common problem in the fishkeeping hobby is the white spots, also known as ich or ick. Ick is not deadly if treated in time.

Ick is actually caused by an ectoparasite (ciliate protozoan Ichthyophthirius multifiliis) and it is very easy to detect. The fish start rubbing their skin against rocks, plant leaves, decoration or to the sides of the aquarium. They can also lose appetite. You will notice small white spots on their skin and fins.

Curing ick is not that hard. There are various medications, but you can also use aquarium salt.

How to cure ick:

  1. Raise the water temperature slowly to 80 F
  2. Add your medication in the recommended dose: I use Seachem ParaGuard
  3. OR Add aquarium salt at a rate of 1 teaspoon per gallon
  4. Keep this stage for 4-7 days
  5. Decrease the water temperature slowly back to normal
  6. Perform a big partial water change of about 70% siphoning the substrate as much as possible

You can cure your fish from ick in a hospital tank; but you also have to apply the medication or salt to the tank, where the fish got sick.

Velvet (Oodinium)

Velvet disease is similar to ick but rarely occurs in hobby aquariums. The body of a sick fish is covered with tiny gold-colored dots (similar to gold dust). This disease is highly contagious and can quickly spread to all your fish.

Velvet is difficult to be noticed in the early stage because the dots are so small. Usually, fish keepers realize too late that something is wrong when the skin of the fish starting to peel off and fish start bleeding.

How to cure velvet:

  • If discovered early, velvet can be cured with copper medication (I had great success with Seachem Cupramin)
  • For best results, turn off the lights on your aquarium until the disease is completely cured
  • Perform 70-90% water changes once your fish are symptom-free

Important: copper medication is deadly to shrimps and snails, so be careful with it. Also note, that once you apply copper to a tank, you can’t keep shrimps and snails in that tank anymore. Copper can’t be washed out from a tank. Be careful with it!

Fin, Tail Rot

Guppy Fin, Tail Rot Disease

Rotting fins and tail is a bacterial infection in guppies. It can also be caused by a fungus that grows on the nipped fins. Usually the fins and tail of the sick fish look like it is stuck together. Poor water quality and ammonia burns can also cause rotting tails.

It is important to know what causes the rotting fin because bacterial infection and fungus are treated in a different fashion.

If the fins and tail do not have any damage but have an obvious sign that is started rotting, most likely it is caused by bacteria.

If the fins or tail is damaged and started rotting, most likely it is a fungus that causes the problem.

How to cure fin, tail rot:

  • Separate the sick fish to a hospital / quarantine tank
  • In case of bacterial infection treated with antibiotics such as Maracyn, Maracyn 2, Tetracycline or Seachem ParaGuard
  • If fin rot is caused by a fungus, treat with special medication – always follow instructions
  • In case of “ammonia burns”, provide your fish with high-quality water

I highly recommend treating your sick fish in a separate tank, because you don’t want to apply antibiotics or medication to healthy fish.

Guppy Disease (Protozoan)

Protozoan is a tiny parasite that affects mainly guppies. It can be also harmful to other fish, but guppies are the most common that gets infected by this parasite.

The parasite attaches to the fish’s skin and slowly enters the fish body through their muscle until reaches the bloodstream.

This parasite usually develops in unheated tanks along with bad water quality.

How to treat protozoan:

  • Add a heater to your aquarium and keep a stable water temperature
  • In early-stage Malachite Green or Formalin can cure this disease
  • In more advanced stages, copper medicine such as Seachem Cupramine should be used
  • After treatment, perform 50-70% partial water change

You can prevent protozoan guppy diseases by heating the aquarium water and doing regular partial water changes.

Columnaris & Mouth Fungus

Guppy with Fungus Infection

Although it looks like a fungus, this infection is actually caused by bacteria. The bacteria colony is usually formed on the fish’s mouth or middle area of the body as a big white splash. The sick fish have trouble swimming because the infection slowly paralyzes the muscle. They also lose their appetite.

The bacteria is highly contagious and mostly affects female guppies; however male guppies can also be infected if the illness is not treated. It can wipe out the whole fish colony in a tank.

How to treat Columnaris and mouth fungus:

  • The key to successfully cure Columnaris is to start the treatment as soon as you see the first symptoms
  • You can use Maracyn antibiotic or Formalin (which is a strong chemical) to cure this disease
  • Adding aquarium salt to your tank can also be effective: do a 50% water change and add one teaspoon of salt per gallon every day for 3 days. Leave the salt in the water until the fish are cured. Perform a big 50-70% water change.
  • A 30 minutes potassium permanganate (KMnO4) bath can also cure Columnaris. Use this treatment carefully. Potassium permanganate is a powerful oxidizing agent and you should not exceed 10mg/l in the bath, because it can burn your fish.

Avoid over-crowding your fish, perform regular water changes, add adequate filtration and ensure good water movement and aeration in your tank in order to prevent Columnaris disease and mouth fungus.


Sick Male Guppy – Dropsy

Dropsy is caused by a bacterial infection that typically targets the liver or kidneys, leading to fluid accumulation in the abdomen that the fish cannot expel. As a result, the fish may appear swollen, discolored, and sometimes distorted. Its scales stand out like pine cones, raised from the body.

The belly becomes bloated, impairing the fish’s ability to swim. This bloating can also result from fluid buildup in the colonic cavity due to factors such as water pollution, genetic disorders, or diet.

Overfeeding blood worms or prolonged high stress can also induce dropsy.

How to Treat Dropsy:

  • Unfortunately, dropsy caused by a bacterial infection can not be treated, because the bacteria cause damage in the fish’s internal organs. By the time the fish presents any symptoms, their damage is so big that there is no return.
  • If the swollen belly is not caused by bacterial infection, there are things you can do: provide the right water parameters and feed a variety of good food.

Some guppy fish keepers reported, that Epsom salt can slow down this disease, and help the fish relax, however, it won’t cure dropsy. If you want to treat your fish, you should not treat the entire aquarium, but you should give an Epsom salt bath to the sick guppies. Put 2 tablespoons of Epsom salt to 1 gallon of water, and put the fish in it for about 30-45 minutes. Make sure that the water has the same temperature as the water in your tank. The best is to use tank water for the treatment in a separate container.

You can prevent dropsy disease by ensuring good water quality and providing a variety of high-quality food.

If you want to learn more about the dropsy disease, please check out my linked article, in which I go into more details.

Swollen Gills and Gasping

Guppies and generally fish breathe by taking water through their mouth, and then releasing it through their gills. They take oxygen out from the water with their rake. Rake is similar to lungs, and it is a very sensitive organ.

Swollen gills are usually caused by ammonia or carbonate poisoning. Ammonia is a highly dangerous toxin. It is the result of decomposing fish food, organic matter and fish waste. Carbonate can be found in different rocks and substrate.

Ammonia in low quantities will burn the gills, which will become inflated. In higher quantities, ammonia is deadly.

Swollen gills also cause guppies to gasp for air at the surface of the water.

How to treat swollen gills:

  • if your guppies has rapid gill movement and are gasping for air, you should immediately do a 50% water change
  • also monitor water parameters during the next few days and test for ammonia
  • stop feeding the fish for few days, because feeding can cause ammonia spikes
  • you can also add nitrifying bacteria (you can purchase API Quick Start from Amazon)

Red Blood Spot on Guppy Stomach / Body

Red Blood Spots on Guppy Fish Body

The red blood spots on the stomach or body of guppies can be caused by ammonia or nitrites poisoning.

This usually happens in new aquariums, which are not cycled yet. A new aquarium can take up to 6 weeks to be fully cycled.

If you introduce fish in a new aquarium, most likely the ammonia and nitrite levels will rise quickly, because there are not enough beneficial bacteria to transform these compounds into nitrates.

Ammonia, in the smallest quantity, is deadly for guppies and most fish. Nitrite is also highly toxic and will cause poisoning and serious damage in the fish.

I receive lots of emails from beginners, who just started their guppy aquarium and their fish are dying for no obvious reason. Well, ammonia and nitrites are an invisible killers.

How to treat red spots:

  • Red blood spots on the belly cannot be treated, but it is possible to save the fish if the poisoning level is not too high and you take action in time

It is better to avoid ammonia poisoning than to deal with it. Please allow your aquarium to cycle for at least two weeks, better is to let it sit for 6 weeks.

If you add fish before the aquarium is cycled, use a test kit to measure ammonia, nitrite and nitrate levels (0 ppm ammonia, 0 ppm nitrite, 10-40 ppm nitrate).

Change water frequently; once a week might not be enough with a new aquarium. Measure the water parameters and change the water if you see any sign of ammonia or nitrite.

You can buy the Seachem Ammonia Alert from Amazon, to constantly monitor ammonia levels. This tool is not as precise as test kits, but it can give you a good indication on the ammonia level.

Reduce feeding or skip a day to avoid ammonia buildup.

Using live plants in your new aquarium is also really beneficial because some plants will absorb ammonia from the water.

Viral Haemorrhagic Septicaemia (VHS)

This disease is caused by a virus within the blood of the guppy fish. The first signs of viral haemorrhagic septicaemia are lesions on the body. Later ulcer and sores will develop and fins will start rotting. Pale gills and bulging eye can also be signs of VHS. The fish will eventually stop eating and become darker in color.

How to treat viral haemorrhagic septicaemia:

Popped Eyes

Fish pop-eye can be caused by a wide range of factors, therefore is very hard to treat. Popped eyes can occur due to bad water quality, bacterial infection, dropsy, fungus, tuberculosis or other internal parasites.

Pop-eye might not be deadly, but it can cause blindness to your fish.

How to cure pop-eye:

  • It is very hard to cure because it is not obvious what is causing it
  • You can start medicating your fish with different treatments, however, you might cause more harm than good

Swim Bladder Disorder

The swim bladder is an internal organ in fish, which is filled with gas and helps in controlling their buoyancy. This organ is also responsible for keeping the fish at current water depth and keep balance while swimming.

In guppies swim bladder disorder is not a very common problem but it is usually caused by high stress: moving guppies from shallow to deep water. The fish will float at an angle or upside down, unable to control the swimming and keep the balance.

Poor water parameters such as high ammonia can also cause disorders in the swim bladder.

This is a video of a sick guppy fish with swim bladder disorder:

Swim Bladder Inflammation

This problem can be spotted very easy, because the fish belly looks distend and starts swimming with the head pointing to the substrate, standing on its head.

This is caused by a virus and unfortunately cannot be cured. Fish with such symptoms should be removed from the tank and destroyed right away.

Gill Flukes, Gill Worms

A tiny white worm that can be viewed with a naked eye causes the gills of the guppy fish to bleed. The fish is constantly gasping for air at the water surface or sits at the bottom of the aquarium having a hard time breathing.

How to treat gill flukes:

  • You have to treat the whole aquarium with special medication – follow instructions. I discovered in the early stage, fish with gill flukes can be saved. However, you can’t do anything for fish with bleeding gills.

Gill worms are introduced in your aquarium usually by adding new fish or plants. This is why is important to keep newly purchased fish in quarantine. Bad water quality will also encourage the spread of gill flukes to other fish.

Camallanus Internal Worm


Camallanus is one of the most commonly found parasites in guppies. This parasite can reach up to 0.8 inches in length and is sticking out from the anus of the fish. It is easy to distinguish from wish waste because the Camallanus has a brown or orange color and has a movement similar to worms.

Occasionally other fishes attack the Camallanus, which is sticking out.

There is no such proof of where the parasite is coming from. Fish breeders reported that these parasites are mostly found in guppies that are kept outdoor in ponds and fed with live Cyclops.

How to cure Camallanus parasite:

  • Camallanus is usually treated with Levamisole (commonly known as Ergamisol) for at least 5 days, but Fenbendazole and Parcide X or D works as well.
  • Perform substrate vacuuming, complete filter cleaning after
  • Do huge water changes: 70-90%
  • After 3 weeks repeat the Levamisole treatment, clean filter and vacuum the substrate again

Avoid feeding live Cyclops to your guppy fish in order to avoid this nasty parasite.

Hexamitiasis – Hole in the Head or Body


Hexamitiasis is caused by a protozoan parasite, Hexamitia. This parasitic disease is rare in guppies. However, there are guppy fish keepers who struggle with this disease.

Guppies infected with Hexamitia produce white, stringy feces and their colors become pale. The infected guppy will lose its appetite and eventually will refuse to eat.

In other fish species such as cichlids, one ore multiple holes will appear on their head. In guppies, these lesions appear on their body.

How to cure Hexamitiasis:

  • Hexamitiasis is usually treated with metronidazole (commercially known as Flagyl)
  • The best way to treat Hexamitiasis is through medicated food
  • If the fish refuses to eat, the medication should be applied to the water – at a dosage of 250 mg / 10 gallons once a day for at least 3 days.
  • In the US metronidazole in available at most pet shops, however, in other countries, it can be purchased with a veterinary prescription

Hexamitiasis usually appears in overstocked aquariums, where the filtration is not adequate. The lack of oxygen and water changes can also be a factor of Hexamitiasis.

I highly recommend oxygenating the water, setting up proper filtration and doing weekly water changes in order to avoid this disease.

Bent Spine (Scoliosis)


Scoliosis, commonly known as crooked back or bent spine in guppies isn’t rare. It is usually a result of genetics and environmental factors.

Typically you will find this disease or anomaly in younger fish. In some guppy fry the scoliosis can be observed only from above, while in others the side view will reveal the bent spine.

Usually guppies with crooked back will have trouble swimming.

Scoliosis is typically caused by in-breeding guppies and it is specific to live bearing fish. The result of scoliosis is slower growth and swimming problems.

Guppy fish with bent spine are usually weaker and often they get bullied by the others. They also have a shorter lifespan.

Reproduction of guppies with crooked back is possible, though is not recommended. Because this health issue is a result of genetics, the parents will pass it to the offspring.

I’ve experienced a bent spine female guppy giving birth to 45 fry. About 90% of the fry had bent spine. So it is very likely that most of guppy fry will inherit this health condition.

How to treat Scoliosis:

  • unfortunately there is no cure to bent spine
  • it is not contagious; however it can be inherited by offspring

Guppies with this disability can still live a good life, if you give them a good diet and good water conditions.

Fish Tuberculosis

Sick Female Guppy: Tuberculosis

Tuberculosis is caused by bacteria called mycobacterium. The first sign of this disease is the lack of appetite, followed by hollow-belly, ulcer on their body around the anus, fin and tail rot, discoloration.

The fish becomes inactive and slowly dies. Tuberculosis can be passed to other fish if they consume the dead body of the sick fish. This disease can also be passed to the offspring.

Tuberculosis in fish cannot be treated easily. Dead fish should be removed from the tank immediately. Fish that are presenting symptoms should be quarantined and treated with Neomycin, Kanamycin or Isoniazid antibiotics. If there is no improvement, sick fish should be euthanized to avoid the spread of infection.

I’ve written a whole article about how to euthanize guppy fish in the most human way. I highly recommend reading it, if you are dealing with sick fish, that cannot be treated anymore.

In very rare cases this disease can also be passed to humans. So be very careful when dealing with sick fish.

Applying Treatments to Your Fish Tank

Depending on the illness you will need to treat only one fish or the whole tank. Before applying any medication to your tank, remove the activated carbon media from your filter, because this can neutralize the medication. Once the medication is over, you can place it back.

Always read the labels on the medication and follow instructions. Never overdose on the treatment, because you can cause more damage to your already sick and healthy fish.

After medicating your fish, perform big water changes to eliminate the medicine from the water.


I really hope this article has helped you to figure out the disease and treatment for your guppy fish.

When keeping fish, is important to check your fish daily and ensure you react fast to any illness. Discovering diseases early is the key in saving your fish from death.

Always have medication on hand, or at least know where to go when you need them.

If you have any questions regarding this content, please let me know in the comments below.


  • Featured Photo:
  • Dropsy  Photo:
Updated: December 14, 2023
Questions & Answers
  1. Hi Fabian
    Thank you for your website, very informative.
    My daughter guppies are in good health except for thier gills are swollen. I can’t find any reference to what might be causing it help plz.

    1. avatar

      Hi Brady!
      I’ve just updated this article and included the swollen gills disease.

      When did you setup the aquarium? Did you add the guppies right away? Is your tank cycled?

      Probably your guppies have ammonia poisoning and you should immediately do a big water change.
      I recommend doing ammonia test using the API Test Kit from Amazon.

      Please let me know if you were able to overcome this problem. Did you lose any fish?

  2. Hello, I need help. I looked at the list of guppy illnesses but cannot identify the one that my guppy might have.
    He mostly just floats in one place at the top of the fish tank, although not upside-down. When I feed my fish, he eats, but is otherwise inactive. I’m really worried, since he used to be so energetic.
    He has this weird bruise-looking thing on his side, and his scales are gone there. He also has this thing sticking out under him much like the picture of the guppy under the fish tuberculosis section does, so he might have fish tuberculosis. In that case, I’m ready to start grieving :'(
    Please help me as soon as possible. We recently introduced a zebra danio and a glowfish danio into the fish tank, and we already have 7 tetras and a MM platy. I really don’t want them to get sick. Thank you!

    1. avatar

      From what you describe here, it might be some type of injury. You only keep guppies in your tank or you keep other type of fish too?

      A picture would help a lot to determine the disease your guppy might have.
      Can you email me a picture of your guppy fish?

  3. My guppy looks exactly as the swollen guppy in the very first picture. He is always at the bottom of the tank. Is that dropsy? I don’t see any scales sticking out in my guppy. He still has a good appetite. Any information would be helpful. Thanks

    1. avatar

      A picture of your fish would help a lot in identifying the problem. Can you email a photo to me via the contact form?

      1. Hi Fabian,

        First of all thank you for this website.
        My guppy’s one side gill is swollen and the color is faded at that area.
        What could be the reason.?
        Thanks in advance

  4. Thanasis

    Hello, i have also a problem with my guppies.
    I have a guppy and it has a white poo like string. Is the third day that observe it. What i must do? I read some articles and i found that this is a desease. I meed your help to save my tank.

    1. avatar

      Hi Thanasis! The white poo in guppies is definitely a sign of disease. It is usually a sign of infection. You should try medicate your guppy with a general medication such as SeachemPara Guard (Amazon link) and raise the water temperature to 79-82 °F (26-28 °C) for few days. Medicating the fish food might also help combat the infection faster.

  5. Hi Fabian,
    Thanks for this very informative article. We started a guppy project at my daughter’s daycare. The type and number of fish were chosen by the manager as I am more specializing in bettas. 10 guppies in a 5.5 gallon. They keep dying one after the other and the manager replaces them periodically. The tank is cycled. Water parameters are 0,0,0 and pH is 7.4. There used to be an old veiltail betta in that tank that passed away and they washed the tank carefully after that. I tested after the refill and ten parameters were fine. Do you think I could be overpopulated and therefore high stress level? That’s the only reason I can think of. What is the optimum number of guppy per 5 gallons? I bought a 10 gallon tank for them yesterday and I can’t wait to upgrade their habitat. I also got live plants. I am planning g on using the 5.5 g for a shrimp project. We never used copper in that tank. Would be happy to hear your thoughts on this. Thanks,

    1. avatar

      Hi Celine! Thank you for your comment.
      If the water parameters are good and the aquarium is cycled, and water temperature is stable, than you should be fine.
      The only thing I can think of is overpopulation. In a small 5 gallon tank, I would place up to 6 guppies. In a 10 gallon aquarium you can go with 10-12 guppies at most.
      The 5.5 gallon tank would be much better for shrimp, so it is a good idea. I actually keep red cherry shrimp in a 5 gallon tank, and they love it. They breed like there is no tomorrow.
      Guppies, though, need more space, so the 10 gallon would be a good start.
      Hope, all goes well with this project! Wish you the best!

  6. Madison K

    Howdy, so I have recently purchased two male guppies online. They arrived in pretty bad condition (about two days ago they arrived). One of them is in pretty good condition by visually examining him. However, it is the second one I am concerned about. 1/3 of him is primarily a cream color. Which this concerns me- a lot. His back fin is pretty much torn up. There are brownish/yellow spots near the base of this injured fin. I was just wondering if anyone could identify this odd spot?He is placed with the other one in a 10 gallon QT tank with java fern. I turned the temperature up to 80 degrees slowly. But I’m stumped to identify what is wrong with him?

    1. avatar

      Most likely this is caused by stress or ammonia burn. How many days did they spend in the shipping box?
      If the shipping stressed your guppy out, it can get better, just feed good quality food and do water changes.
      If it is ammonia burn, it might never get in his shape again.

  7. Hello,
    I am concerned about one of my guppies and wondered if I could email you some film footage I took off him as I am struggling to identify if there is an issue.

    1. avatar

      Hi! Through the contact form you can’t send me video file, but I’ve sent you an email.

  8. Hi Fabian,

    I have noticed some odd behaviour with my guppies ( all male) one is very fat, if it were female I would say it was pregnant, all the other guppies are constantly surrounding him. He has no colour loss etc and seems to me to be healthy.

    1. avatar

      Hi Jay, can you send me a picture of your guppies using the contact form? Maybe I can help, if I see a picture of them.

  9. Hi Fabian, thanks for the quick response. I have taken some pics however the file size is too large to send through the contact form. He has overnight developed a fine hair like strand with a white bobble on the end, which is coming out of his anal fin.

  10. I bought 3 male guppies yesterday, added to a new tank with good paramnters after a failed fishless cycle. I noticed that one had a fuzzy white growth on its Gill this morning, only 12 hours home from the store. Under the fuzz is a red inflamed spot. Since I just bought the fish, I brought it back to the store for them to deal with. The other two fish look fine. I’m hesitant to treat the whole tank and I don’t know if this is fungal or bacterial since the symptoms I listed sound similar for both. Can I just watch the other two rather than treating the tank? I did add 2 tablespoons of aquarium salt this morning as a natural treatment/prevention. Thoughts? These fish were in the same tank at the pet store and only in my tank for about 12 hours. Thank you!

  11. Hello Fabian. I added three guppies to a new tank yesterday after a failed fishless cycle. Less than 12 hrs in the tank I noticed a fuzzy white growth on the gill with red inflamed spot underneath the fuzz. I brought the fish back to the store since it was just bought. I added 2 tablespoons of aquarium salt to the tank to boost bacterial fungal prevention properties in the water. I’m hesitant to treat the whole tank but wanted your opinion. All parameters are good and it’s only two guppies in the tank now, no other fish. Can I just monitor? Also, after some research, the symptoms seem like it could be bacterial or fungal, so I’d hate to treat with the wrong treatment. Again, fuzzy white growth with red inflammation underneath the fuzz on the gill area. Fuzz was the size of a point of a pen and the inflamed spot about an 1/16 of an inch. Thoughts?

    1. avatar

      Hey Brooke,
      can you send me a photo of your fish? Please use the contact page and attache a picture to the form.
      Is your tank cycled? Have you treat your water with a water conditioner? Is your tank heated? Have you tested water parameters?

      Red inflated gills are usually caused by ammonia or chlorine.

  12. Thank you Fabian for replying! I actually already brought the fish back since I bought it only last night. My only hang up is whether to treat my tank that holds my two other guppies. All parameters are good including ammonia, PH, heat, hardness. Like I said I tried a fishless cycle for 2 months, it failed, I think because I used my well water that went through a softener, so no minerals to help the nitrifying bacteria grow. So I decided to do a new tank with half untreated well water (bypassed my softener) and half bottled spring water. I used tetra safe start, I know it’s not ideal to do it this way, but I’m going to do my best to keep these guys comfortable. I tested my mix and was happy with the results so I think I’m off to a good start other than the pet store selling me a sick fish. The spot was literally a spherical shaped fuzzy white spot attached to inflamed skin on the surface of the gill area, the gills themselves seemed ok. If this was fungus or bacteria, can I do a wait and see on my other fish rather than treat the tank? I hate to expose the other two to meds and turn my tank green. Thank you

  13. Hi, I actually have 4 guppies (2 males and 2 females) and 2 small goldfish (2 inches) in a 10 gallon tank. I have kept them for a month now and I’ve been doing Water Change either every day or every 2 days, depends on the water quality which I always check and test every day. So far my water quality seems to be just fine, pH is around 6.8 and 7.4, ammonia 0, Nitrites 0, Nitrates 5 or maybe below 5.

    All the guppies are doing fine until just now after doing a 60% WC, I just noticed that one of my female guppies has a weird lump or blister on her body. She swims and eats normally, but I think she’s breathing kinda hard unlike all the other guppies.

    this is the video of her. What is wrong with her? Is it some kind of skin disease? or Dropsy? or tumor or something? Is it contagious? Should I quarantine her? I’ll do another 80% WC tomorrow for precautions.

    1. avatar

      Hi! This looks like a tumor. I don’t think it is contagious, but I would separate her from the others.

  14. Sharon

    Hi. My guppy has a completely clear what looks like a totally clear bubble/blister on its top little fin. Where it attaches to the fin itself is a little black mark. I’ve looked up some diseases but can’t find anything like it. The fish is acting normally apart from occasionally rubbing past leaves of plants. I used ‘Love Fish’ branded anti bacteria and fungal treatment and over 7 days it’s now not hardly itching itself and maybe the smallest of improvements in size of the blister/bubble. Apart from that it seems fine. Its our only guppy (others died months ago of we think old age) but also have 2 neons and a cat fish and a loach which are all fine. Any ideas please.

    1. avatar

      Hi Sharon. A photo of your guppy would help a lot in determining what the problem is. If your guppy is old, this might be a tumor.
      Please send me a photo through the contact form.

  15. Susannah

    Hi. I have had beta fish in the past, but this is my first time having guppies. I got 6 yesterday: 4 elder guppies, 1 Sunburst platy and 1 delta guppy. All of them were marked as male. They are all totally fine and never stop swimming, with the exception of the delta. He is not showing any extreme signs of sickness, except that he does not swim very much. He is not dead, because I can see that his gills and fins are moving. He does not have any discoloration or anything like that, but simply either sits at the top of the tank, or glides around the bottom. I was starting to think that he had a bent spine, but when I looked up images of that they did not match what he looks like. His back is mostly straight, and not curvy like the images I saw online were like. I have a filter, heater and light, but I do not keep the light on at night so as to allow them to rest (I read that they will be unable to sleep, causing death if you leave the light on). It is a ten gallon tank, so there is supposed to be enough space for them all. Any feedback of what this may be would be extremely helpful! Thank you so much!!

    1. avatar

      Hi! Maybe the delta guppy is just stressed out due to transportation or new environment. If it has no sign of diseases, just give him few days.
      If you want, please send me a photo of your guppy fish via email.

  16. Susannah

    I would be happy to send you an email, but I do not know what your email is.

  17. Susannah

    Though he was getting better, however this morning I woke up only to find him lying upside down on the bottom of the tank. I thought fish were supposed to float when they died, but I’m pretty sure he’s dead. I think I will go get a new sunburst platy and not have a delta. I think I like the platy better. Just so I know for next time, how is the best way to transport them that they will be safe?

  18. Samuel

    I have three guppies in a 40 gal. I have had them for over two months. I observed today that two females have white stuff on their mouths and one has some on it back( over the eye back) and on its fin. It is not ick. How should I treat it ASAP? Thanks

  19. Hello. I have a tank of five guppies. And all of the sudden one of them got this red bloody looking stomachand around where their front fins are. And the first one on the bottom of its stomach looks as it’s deteriorating. The others have started to get the red also. Do you have any idea what this is and what could cause it?

    1. avatar

      This sounds like ammonia poisoning, but maybe I’m wrong. In any case, do a 50% water change on your tank. Can you send me some photos please via contact form?

  20. Alan Haight jr

    Would you know any breeders that send free sample guppy breed’s for a handicapped veteran I know. Would like to see him up and about more. Think it would motivate my friend. He left for service leaving behind over 20 tanks with his mother in charge of care. But unfortunately his mother passed away and all the fish lost. I have no money and can only find any guppies at Walmart that die. Please let me know if you have any breeders that could help me out with this. My friend is going through a lot and this might be what saves him.

  21. Ashely

    Hi Fabian, Thank you so much for this article. I’ve checked it a number of times and it really helped me learn a lot. I’ve just sent a message w/photo to you for seeking your advice on whether my guppy has TB. Many thanks for your time!

    1. avatar

      Hey Ashely, I’ve just replied to your email. Hope you find it useful!

  22. Megan Macdonald

    Hi there my guppy is swimming at the bottom with her right eye against the glass and almost looks like shes hoping I cant figure out what it is please help me I

  23. beatriz

    hi, i have had my four guppies for more than two years now, which i now places them at risk of dying of age. they are all from the same offspring, all males and until this morning all healthy. they are kept on the same tank for the past two years and they don’t have a water filter but the water is changed every two weeks and i have water bamboos. this is the set up i’ve had all along. this morning i woke up to feed them and noticed that one of them had a protuberance out of its stomach, like it’s guts were coming out. i had noticed in the last few weeks he has had the odd behavior of hiding and only coming out to eat when i call them (gently tap on the glass and they all know it means food). i immediately separated him to a jar because the others seem to be trying to pick at him. aside from this he seems healthy and eating normally. but upon inspection of the others to see if they were ok i noticed that one of them ha it’s top fin hanging and is is filled with tiny bubbles that look like some sort of tumor (it doesn’t look like gas bubble disease, and i think if it was it would have showed up yearlier). he aside from this appears to be healthy (is swimming and eating just like the other two). now i know they are old and have exceeded their lifespan but i still love and care for them and want to take care of it if possible. i don’t have much experience so i don’t know what to do. if needed i can send photos to you if this means you can help. please i don’t know what else to do.

    1. avatar

      Hi Beatriz. Guppies will develop diseases due to old age and weakened immune system. Once they get old, their immune system will become less effective. Probably this is the reason why your guppies get sick, even if you follow the same routine for two years. If you want, you can send me some photos of your guppies via the contact form.

  24. Theresa

    I have a purple female guppy that I just purchased. I didn’t look at her very well when I bought her. So I don’t know if the lighter pale purple to whitish spot about 5cm diameter near her right gills is her natural coloring or a disease.

    1. Theresa

      My purple guppy in question won’t let me catch her to get a better look at her

    2. avatar

      Guppies and most fish tend to lose their color during transportation or when introduced to a new environment. I don’t think it is a diseases, however, you can send me a photo of here via the contact form. I can give you a much better response if I see a picture.

  25. I’m not sure what’s wrong with my guppy. Some say it scoliosis ors say tb, help?

    1. avatar

      It is an adult guppy that started developing a bent spine? It may be a sign of TB, however from my experience this can also develop from bad water quality.
      I suggest testing for ammonia and nitrites.
      Recently someone contacted me with the same problem. After some email conversation she realize that ammonia level was at 2.4 ppm – this caused the whole problem and resulted in sick and dying guppies.

      1. She is the o lay one and all the levels are with in the normal range

  26. Peter OConnor

    My son just bought a new male guppy for his tank and within 12 hours he started to lose colour and his tail thinned. The other previously healthy 3 guppies began to be less active. The new fish and a female died and the other two have died in consecutive days. The tank water was all clear and tested at the shop. Ammonia levels not detected! There is a white coating in the tank on the filter and glass. Can one new fish turn a healthy tank into a death tank? What could this be?

    1. avatar

      Hi Peter. This is unfortunate! Indeed a sick fish can make all inhabitants sick. I can’t tell what type of disease it is, but it sounds terrifying. Are you sure that water parameters are good? Such a huge death rate in such short amount of time can only be caused by ammonia in my experience.

      1. Peter OConnor

        Thanks Fabian
        I’m not sure but have done a 3/4 tank empty and the cloudiness has disappeared which would indicate ammonia! I’ll repopulate slowly just in case once all has settled.

  27. Fabian Roudra Baroi

    Hey Fabian . I had some ich problems with my fish, then i shifted them to my hospital tank and raised my water temperature , also added aquarium salt in it and after 3 days it is looking fine, so can I transfer them to my original tank or wait 2 days more? And some of my guppies are affected with both fin rot and ich , can I use both medicines together ? Will it work?

    1. avatar

      Hi! You can use both medicine and salt in your aquarium, however I would recommend treating your main tank as well. It is not enough to treat ick on only affected fish. You need to treat the entire tank, because ick has a relative long incubation period in which salt and medicine will not affect it. Even though you treat your fish, the ick “eggs” can still remain in the tank, which will make your fish sick again.

      1. Fabian Roudra Baroi

        Thanks for the help Fabian and can i remove the fishes to another tank which is cure or wait for at least 5 days of medicine course??

  28. I need help I don’t know what my guppy has I think he is dying now but I’m not sure from what this has happened to two of my guppies already I have pictures

  29. Ghada Salah

    I have 3 females and 2 males , one of the females isn’t active since yesterday, it is sticking beside the filter , but when someone touches her it overreacts for a moment then turn back to being very calm as if it was dead .
    What should I do to help her ?!!

    1. avatar

      Does she has a swollen belly? Maybe she is pregnant and in labor. It is normal for female guppies to hide or to just become inactive when she is in labor. You could place her in a different tank, but it is not necessary. It takes about 1-2 days to release the fry and she will become “normal” again.

      1. Ghada Salah

        Thanks for your support
        No she doesn’t have a swollen belly
        She doesn’t want to eat
        She swims up to half the tank then rests back on bottom without reaching for food , even after food sinks in rocks she doesn’t try to eat it 😢

  30. janke maritz

    just recently a few of my guppies have been spotted with white bumps all over their body/fins, and their fins are all torn on the ends… i’m really not sure what it is. At first i thought it was white spot disease and so i got treatment for it but it hasn’t really made a difference.

    what should i do ??!!

    1. avatar

      Hey! This is most likely ick / ich. You should follow the instructions of the medication.
      It requires some time to cure this disease. It can take up to 4 weeks to get rid of this parasite from your tank.
      I suggest reading the steps from this article to learn how this disease work and how to cure it.

  31. Ashley Strong

    Hi Fabian,
    I keep and breed guppies and your article has been most helpful. I do have an issue occurring in my fry tank that isn’t described in the article. I have many fry that have a “pin tail”. After a bit they die and lay on the bottom. They become covered in a white fuzz that reminds me of dandelion fluff. Any assistance you can give would be most helpful!
    Thanks again,

    1. avatar

      Hey Ashley! This sounds like some sort of fungus. This disease usually occurs due to poor water quality. Try to do water changes more often and do not overfeed your fry tank.

    1. avatar

      You need to eliminate ammonia completely. Ammonia level should be at 0 ppm at all time, expect if you are cycling the fish tank.
      You can lower ammonia level with water changes or using Zeolite in your filter.

  32. Alexandra

    Hi Fabian , I have read your article and find it really good but I can’t seem to find the illness that keeps killing my guppies for months now , Tank was cycled for a long time , water changes once a week , good water parameters , at some point I added some guppies from someones tank and thats when one by one they started getting ill , nitrates went veryy high ..despite the frecvent water changes , I treated them for fin rot and parasite but succes ..they lose weight but they still have appetite , they are active untill the last couple of days of their life , their fins rot and get darker or lose their colour ,poop stringy , they just keep dieing no matter what I do , I separated them from my main tank , It only affected the guppies and no other specie in my tank . Any ideea what I am dealing with ?..maybe I can save the last remaining ones ..

    1. avatar

      My guess is that you have ammonia spikes, probably after feeding your fish. Ammonia in low quantities will make your fish suffer and will cause organ failure which will result in different kind of diseases. Because the source of the diseases is not directly a bacteria or parasite, you can’t really treat it. You have to fix the ammonia problem first.
      Make sure, that you have proper filtration with good biological filter media. Please give me more information about your tank such as size, filter type, number of fish in your tank.

  33. SOheyla

    Heyy fabian. I need help with my guppies. So I bought this used 35 gallon tank from a lady. The tank was still running when I picked it up but since it was very dirty I took the tank and washed it but left the filter media just as it was. The tank came with few fish which includes empire Gudgeon, Algae eater, Gouramis and a cat fish. After setting up the tank and waiting few days I added my guppies. But few days later I found one guppy dead. By the time I didn’t think much of it. But now it’s being a week later and I keep losing guppies. One guppie a day if not two. I notice that few of my guppies have a clamped tail and it swims around like dragging its back. If you can let me know what this might be and how I can treat it to save the rest of my guppies will be great thank you !

    1. avatar

      Hey! If all other fish are fine, then probably your guppies are bullied and stressed by the others. I think that the empire gudgeon might bully your guppies. Keep one eye on this fish, because they don’t go very well with long fin or smaller fish. Empire gudgeon can grow up to 4 inches (10 cm) in size. I wouldn’t recommend keeping guppies with empire gudgeon together.

  34. Alexandra

    Hi again , tank is 100 liters, I use a stingray as a filter (later on I added another filter called tetra something ) , and fishes in the tank 7 mountain cloud minnows , 4 bronze corys and 8 neon tetras and the guppies .but now the guppies left I moved them in another tank .the tank is with live plants , I tested for amonia but I never got anything , I had a problem with nitrates but that went down now ,now most of the guppies died ..and each with diffrent simptoms…I have 4 left and only 2 seem sort of healthy ..the other two it looks bloated and other one way to skinny ..I feed them quality food and frozen food and once in a while pea .thank you for your reply

  35. Alexandra

    Im starting to doubt my testing kit , maybe its expired or something .I will buy a new test just in case , I had some Strips one and the one with the disolving tablets .

  36. I started to order ParaGuard off Amazon for my white poop guppy. It states not to use in a tank with sharks.
    I have a rainbow shark in my tank for cleaning the bottom of the tank along with a Cory cat.
    Will the ParaGuard affect the rainbow shark?

    1. avatar

      Hey Diana, I’m not sure if ParaGuard will affect your shark or not. Probably you should ask the manufacturer about this. To be on the safe side, I would treat the guppies in a separate tank.

  37. Hi, I have Red Delta Guppies and one male developed about 5 black spots on his body and tail, they are not a dark black. He is eating and acting fine. I moved him to a hospital tank and before I put him in most the spots were gone except a couple on the tail. Your help is appreciated, I’ve searched the internet with no luck. Thank you

    1. avatar

      Hello Mari. I’m not sure what causes the black spots on your guppies. Can you send me a picture of your fish via the contact form?

  38. Hello Fabian

    Thank you for the info, it was very helpful however I looked at my fish yesterday and they were fine but today when I looked one of my female guppies tail was covered by this clear stuff and it was super clumped together it looks like it has no tail at all just this weird clear thing at the end of its body, it also has a long with string looking thing coming out of its stomach, it also will not come out of the corner of the tank, I have been searching everywhere for any info whatsoever but I cannot find any anywhere please help me.

    1. avatar

      Hey Aidan. From your description it sound like some sort of fungus or bacterial infection but it can also be ammonia burn. Most fish, including guppies are very sensitive to ammonia, which is produced by overfeeding and fish waste. Only one guppy has these symptoms? Have you checked water parameters?

      Most diseases come from poor water parameters. This is especially true in case of newly setup aquariums. I highly recommend testing for ammonia, nitrite and nitrate first. These should be at: 0 ppm, 0 ppm, 10-40 ppm.
      If the tests results show no ammonia and nitrite, then most likely there is some sort of infection in your aquarium.

      Please send me a picture of your sick guppy fish through the contact form if you can.

      1. I will do a water test the see what is wrong thank you.
        also that long thing at the beginning is the image address

  39. I will do a water test the see what is wrong thank you.
    also that long thing at the beginning is the image address
    yes it is only one guppy.

    1. avatar

      This looks like fin rot – it could be due to poor water quality or some bacterial infection. If the water parameters are good (0 ppm ammonia and 0 ppm nitrite), then you should treat the tank with Seachem Paraguard. If water quality is not good, you should fix this first.

  40. justine

    I need major help please! I have a 20 gallon tank, temp is 80, Nitrate, Nitrite, and ammonia are at 0. I have 4 guppies, 2 male, 2 female, and they get along really well. I had 2 other guppies (male and female), but the female died of TB and the other male died of the symptoms I’m about to state. The tank has been up for 4 almost 5 months, it has been cycled, I have hiding places, 4 amano shrimp, a sucker fish and the carbon is taken out of my filter. I also have medicated my fish with Furan-2 thinking it was a gram negative bacterial infection.

    Symptoms: Both of my males (the one that died and one of the living ones) started off healthy. Their fin started to go from circle to rectangle, then finally like a V shape (point end on the end of their tail.) It took about 3 to 4 days before the first make died. Their backs are black but seem to dull. Their top fin is lowered to their body and the side fins are perfectly fine. They tend to hang at the top op my tank, swim around just a little bit, but never leave. Their appetites are fine until their back fins look like a V.

    I have added aquarium salt, change the water 10-15% weekly. Before the Furan-2 treatment, I gave them Melafix. What is the disease causing this? What is the cure?Is it preventable?

    1. avatar

      Hey Justine. Fins of guppies usually collapse due to bad water quality. I think that your tank experiencing ammonia spikes, which can be really harmful for fish even in low quantities.
      Maybe the medication killed off some of the beneficial bacteria in your filter and was not able to deal with the produced ammonia. In a healthy aquarium nitrate should be around 10-40 ppm. If you measure 0 for nitrate, it means your filter is over-filtering and produces a full cycle (which is really good), or the aquarium is not cycled yet. I think that your aquarium have started a new cycle after medication, which, in the long run caused more problems.
      After medicating the tank, you should always put the carbon filter back to filter out the remains of the medication.
      After that, you should use beneficial bacteria, to boost the filtration (I recommend this product from Amazon).

      1. justine

        The male passed away. Now I have one male and 2 females that seem to be doing fine/better. The females started to scratch themselves on decorations hours after I posted my first response. As soon as I read your response, I did an immediate water change or 50% and will continue to do 10-15% every 3 or 4 days. So far the other guppies seem to be doing well, the females have stopped scratching and have gone back to normal. My filter is set for a 20-40 gallon and I have a 20 gallon, so I set it to 30. The carbon filter is back in as well. I have also been adding beneficial bacteria to the tank and will continue to do so for a week or two. I will test my tank again, when I did test it, it was about 3 or 4 days prior to commenting here. I greatly appreciate your help. I do have one last question, how long should I wait before adding more fish to my tank?

        1. avatar

          You should wait until the thank is established. There is no purpose of adding more fish, because they will eventually die. I would wait at least 2 months with adding new fish. Also, consider getting a bigger filter. Manufacturers tend to overrate their filters. Usually a filter, which is rated to 20-40 gallon tanks, would not be able to filter a 20 gallon tank properly. Most likely will be enough for a 10 gallon aquarium.

          In case you overstock your tank, you need a much bigger filter. If you overstock a 20 gallon tank, you will need to consider a filter which is rated to 50-100 gallons, or you will need to do water changes every other day to keep your fish alive.

    1. avatar

      Seachem Prime is a water conditioner. This product will remove chlorine and heavy metals from tap water. It can’t be used to treat any disease.

  41. Hi Fabian, I noticed one of my guppies has a small lump sticking out from its lower body. She doesn’t seem ill or inactive or lack of appetite but it certainly looks like your picture under Tuberculosis. Does she really have the disease as it sounds deadly? I have sent you a photo I took through your contact form. Hope to seek your kind advice. Thanks a million!

    1. avatar

      Jyn, I’ve seen the photo. This looks like ulcer, but can’t say with certainty what is causing it. I don’t think it is tuberculosis, because he does not have a bent spine. Unfortunately, ulcer can’t be treated. Your other guppies are fine?

      1. Thank you Fabian, how will an ulcer affect the guppy? Will it be healed? The rest of the guppies are normal, many thanks!

        1. avatar

          The ulcer is a condition caused by a disease. In the long run, is deadly for the fish. I’ve never seen a guppy to heal from ulcer.

  42. Emma Godwin

    Dear Fabian,

    Thank you for your helpful website. I have a 20 gallon tank which has been up and running for 6 weeks. It has 6 corydoras catfish and I have recently added 3 male guppies (I am planning to add some more but am stocking the tank slowly). All the parameters have been fine and I am doing a 50% water change every week.

    The guppies have been really happy until yesterday when I noticed that two of them have a red patch which has now turned brown on the back of their head and tracking down their back as if they’d lost some scales. They are still very active and feeding well. I am worried it might be bacterial infection but as I am new to fish keeping and some websites say not to use medication, I am a bit worried about using the wrong thing and causing more problems. But I also found another website that says sometimes there might be random spikes in the ammonia levels, especially in new tanks, and thought it might be a burn on them instead. I have done a water change and added some beneficial bacteria in liquid form. However, I really don’t want the fish to be suffering and would be grateful for any advice you can offer.

    Thank you for your help.

    1. avatar

      Hi Emma. It is likely to be an ammonia spike, which can make your fish suffer, especially in a new setup. Ammonia is one of the common problem in new aquariums.
      Instead of 50% weekly water change, I would do two 20-30% water changes a week. In new setups it is better to do more frequent water changes, rather one big water change.

  43. Shannon Wise

    need alittle help, adorable male cobra guppy swole up about a week ago. Is still living his best life and he isn’t getting any bigger, no pine cone fins, eating just the same, swims to the bottom with no problem, swims just fine….just fat all the sudden. Have fed green peas one day, ate them fine. haven’t seen him poop but I have never seen him poop honestly. help….please

    1. avatar

      Well, if you don’t see any other sign of disease, maybe you should not worry too much about your guppy. Bloated body can also be caused by an organ failure (liver or kidney), which can not be treated. So I recommend to enjoy your fish until you can.

  44. My Guppys have the following expression. I bought them one month from now. Thanks to you help me their kind of illness and treatment. I am very grateful to you.

    – fishs swim and rub their bodies against the bottom of the lake and trees in the lake continuously. Fin and tail are normally, not torn.
    – Shaking, bending and feeling uncomfortable. They are like be itching. They still eat for the first 1-2 days
    – More severely ill fish shake gently and stop eating. This manifestation usually appear on the 3rd, 4th day from the first day of illness.

    1. avatar

      Most likely ammonia is the problem. They will rub their body to aquarium decoration because ammonia burns their skins and gills. They will stop eating because ammonia affects their internal organs and finally their immune system or their organs give up and die. This is very common in new aquariums.
      You should feed less and do frequent water changes. In the beginning you should do 20-30% water changes twice a week.
      Also feeding your fish once a day or once every other day is enough. Especially in the beginning.
      Hope this helps and you can figure out to make your tank stable.

  45. Ryan Jackson

    Good evening Fabian. I am new to looking after fish, I am now into my 4th week and have already had lots to deal with. All was going fine until last week when one of my guppies was not swimming to good. So I brought some swim bladder medicine. This worked a treat with three days and guppy back to normal. However to put the medicine in the tank I had to remove the filter and leave it in the tank for 7 days. Pump was left running. Within this time I lost two oto catfish. They complety disappeared. I think my shrimp cleaned up. Two days ago one of my guppies has now got his tail dropped. He’s still eating and always chasing the other guppies around. What can I do? Can I get medicine for this?

    1. avatar

      Hello Ryan.
      Your tank is not cycled yet! This is the main problem. There could be ammonia spikes still in the tank, which affects the immune system of your fish and develop different diseases if they don’t die instantly.

      Please tell me which medicine you used. Most medicines do not require to stop the filtration. Indeed, the filtration is required while medicating your fish tank to help maintain the system balanced. You only need to remove the activated carbon from the filter, because this is responsible from removing chemicals from the water. Activated carbon will neutralize medicine, this is why you need to remove it while you medicate.

      A new fish tank can be considered cycled after 6 weeks. Beneficial bacteria which gets rid of ammonia and nitrites require a lot of time to populate the filter media and water column.
      My suggestion is to add nitrification bacteria to your tank – you can use the Fluval Biological Enhancer (from Amazon), which helps in eliminating ammonia and nitrate and helps in developing a healthy ecosystem right from the beginning.

      I would avoid medicating the fish, because some medicine can kill off beneficial bacteria.

      Be patient and do not introduce new fish, until everything is stable. Probably it will take you another 4 weeks until the tank is cycled.
      After everything looks stable, you can add new fish, but don’t add too many at once.

  46. Crystal Angel

    Hi Fabian, recently, most of my younger guppies are dying. A lot of those who are nearing death would float at the surface of the tank sideways or not move their fins at all. When gently nudged, they start to move again but will soon return to the original position. Some may even float upside down and seem to be unable to keep their balance, but their stomach looks like they are at normal size so it doesn’t seem to be swim bladder disease. They live in a planted tank that was upgraded to a bigger size since two weeks back, but it was only three days ago when this behaviour started to happen. Any ideas what they guppies are facing now? They are 1-2 months old.

    1. avatar

      Hey! Is this a brand new setup? I think that this is ammonia poisoning. When suddenly most of the fish get sick or die, it is a sign that your tank is unbalanced and there are ammonia spikes. Guppies are very sensitive to ammonia and even the smallest amount will make them suffer. I’m sorry about them, but probably you can’t save them, even if you do water changes. They have already been affected by ammonia and this can’t be fixed…
      When you setup a new aquarium and you fish-less cycle it, you need to introduce new fish gradually to give the tank the time to process that ammonia produced by each fish.
      Your new tank was able to process the ammonia for 3 days and after that ammonia has started to build up and make all your fish sick.

  47. Please tell me what’s wrong and how to fix him. It seems to be acting fine but this clear swollen bump showed up out of no where on the left side of him. He swims at the top of my tank, and doesn’t go to the bottom at all. The lump it kind of see through, so that you can see inside of him. Please help me!

    1. avatar

      This sounds like swim bladder disorder. As far as I know, you can’t treat this problem. Check water parameters and test for ammonia and nitrites, because these can also affect the swim bladder.

  48. Hello my blue guppy has some blue stuff on his head and it has spread to his lips. He seems fine. I just changed the water yesterday and he had it on his head but it wasn’t on his lips. He is in a 10 gallon tank with two other guppies who don’t have anything wrong them thankfully. I had two zebra danios die last week I think that my aggressive zebra danio killed them. I have taken the aggressive zebra danio out the tank because it was stressing put my guppies and I didn’t want them to be sick. Do you have any idea what it is. It definitely isn’t black it is like blue grayish my guppy is blue but i don’t think it is supposed to be blue on its head and face. Thank you so much

    1. avatar

      Hey Numz! It would be best, it you could send me a picture of your guppy via the contact form. I have no idea what that could be. Actually I’ve never seen something like you described here.

  49. Hi Fabian,

    My guppy is experiencing issues. He compresses his tale almost to a point. He also is curving his body a little in a sideway zig zag way. Not necessarily dropping down. His color looks fine. He does eat. Has no patches. Just don’t sure what is wrong with him. I tested the water. There seems to be no ammonia or nitrate build-up. The PH level is good. We have quarantined him just in case but I really would like to know your thoughts on what is wrong with him.

    1. avatar

      Hey Cat! If there is no sign of ammonia poisoning, most likely is fin rot. This is caused by some sort of fungus, which can easily be treated with Seachem Paraguard for example.

  50. Hi 2 of my female guppies just died. Any idea what from?
    All the females were fin clamping and breathing harder than usual. I treated with api general cure. Then 2 of the females died. Symptoms: the two that died were quite fat and were breathing harder and had raised gills.

    The left over females no longer fin clamping but all fish in tank seem irritated. I did a 40% water change.

    1. avatar

      Hi Sarah. Most likely an ammonia spike caused all the trouble in your aquarium. Clamped fins, raised gills and fast breathing are obvious sign of ammonia poisoning.
      Doing a 40% water change was a good decision. Now reduce or cut off feeding for a few days.
      When did you start the tank? If it is a new tank, then probably it is not cycled yet. It takes about 6 weeks for a new aquarium to be consider cycled.
      If you have your aquarium for a longer time, probably you need to consider upgrading your filter, because the current one can’t keep up with the produced fish waste.

  51. Fabian,

    One of my tanks got infected with a disease & I can’t figure it out. I tried treating for bacteria & fungus but nothing seems to work. The last med I tried is Furan 2 but I’ve also tried ParaGuard, Pimafix, Melafix. The last adult died & it was filled with very pungent yellow mucus. I’m left with a tank full of fry & no idea how to help them. Starts out as a white patch on the fish that seems internal

    1. avatar

      Hey Jenn. From what you described here, it sound like a fungus infection. Though, the sudden deaths can be caused be ammonia poisoning, which is caused by poor water quality of lack of filtration.
      Adding so many medication to your tank will not help. Furan 2 is an antibiotic, which will kill bacteria – both harmful and beneficial bacteria. ParaGuard is mostly used of fungus and external parasites and can also affect the health of the aquarium.
      I suggest adding activated carbon to your filter and remove all the leftover medication. Do a 70% water change and monitor the fry. If you see any sign of diseases on them, get in touch with me via email and send me a picture of the fry. Also add beneficial bacteria to your tank in order to prevent any more ammonia spikes.

  52. I now have one fry with a white patch. I can send you a video. Just not sure how to get it to you. The guppies don’t die right away, they linger for a few days, then stop eating & die. Feeling pretty helpless watching it happen. 😔

    1. avatar

      Hey Jenn, I’ve received the picture. This looks to me like fungus. Usually the Seachem ParaGuard helps, but I don’t know why in your case didn’t worked.
      You can also try out aquarium salt (1 tsp / gallon). Guppies will tolerate this amount of salt, and maybe the fungus outbreak will be reduced and eventually eliminated.

  53. Hi Fabian – I have a 20G tank with 14 guppies, 3 otocinclus. One oto developed a fuzzy spot on his back, while I was doing research online, he died. I pulled a worm-like thing out of his back that had hard, horny spikes and 2 at its head like horns. Someone told me the white fuzz might be a fungus and I should treat the entire tank, the worm was a planarium. I don’t believe it was. I was advised to use maracyn and Ich-X. Now about 5 fish are infected, but what they have is a totally white belly. The first guppy that had symptoms had a fuzzy belly. When I started Ich-X, the fuzz went away, and then more fish developed this white belly but no fuzz. I added aquarium salt but instructions said 1 tablespoon/3G. I’m also slowly turning up the heat, doing 25% WC every other day, replacing salt volume. Should I increase salt? Do I add additional salt on non-WC days? Am I using the right meds? How high can I safely turn the heat up w/o cooking my fish? It’s been 2 weeks, another oto died but had no fuzz, 2 guppies died but had no white belly. Do you know what this white belly might be? Any suggestions? I’m so afraid I’m going to lose my whole tank. My tank is very heavily planted, pH is 7, ammonia is 0.25ppm, nitrites, nitrates 0. I’m also using daily Prime and API Quick Start to decrease the ammonia. Should I be using kanaplex or furan-2? I have maracyn two on hand as well as treetea oil, garlic guard, and vitamins. They’re all eating well, in fact they act like I never feed them. Anything you can suggest would be most appreciated.

    1. avatar

      Hi Deborah! First of all, ammonia and nitrite should be at 0ppm!!! From what you described, it looks like your tank is not cycled yet. On top of that, adding medication (antibiotics) to the tank will cause even more damage. You need to fix this first. You will need to help the tank with beneficial bacteria. I use and recommend the Seachem Stability for this purpose.

      The fuzzy spot on the back of your fish might be caused by a parasite. What you described above, looks to be anchor worm. This can’t be killed off with antibiotics. These parasite attach to the fish and will cause infections.
      You need to treat the tank with a dewormer. I recommend this product from Amazon.

      1. Hi Fabian – just wanted to let you know that I’m using the microbe-lift lice and anchor worm you recommended. I haven’t seen any more worms in my main tank since the one on my otocinclus, but interestingly, I bought a pair of Moscow black and blue guppies online, set them up in a brand new 5G with new substrate, heater, filter- new everything, and 2 days later saw a small “string” hanging from his belly. At first I wasn’t sure if it was a fin or something else. Next day it was longer and I felt for sure it was an anchor worm. When the med arrived from Amazon, I treated the quarantine tank. Directions say treat once a week which sounded so long between treatments, but 2 days after the initial use, the string was shorter and the next day it was gone. I will still continue the recommended treatment protocol for both tanks. I would just like to comment to everyone out there, please be careful where you buy your fish from. You like to think everyone takes care of their fish the way they should, but they don’t. If I learned anything it’s quarantine, quarantine, quarantine. That’s how I got into this mess in the first place. I’ve lost hundreds of dollars worth of fish because one pair of fish along with plants from the same place were infected, and I didn’t quarantine. I’ve had DOA fish arrive in disgustingly filthy water. It’s sinful. And you can’t go by online pictures. I’ve ordered the same strains of guppies that were going by different names, the pictures didn’t look like the fish that arrived, and I ended buying strains that I clearly already had. All because I was impatient. You just can’t be impatient with fish. I’m about to start setting up a 55G and I believe I’ve learned from my mistakes. I need to separate my females and males otherwise I’ll be overwhelmed with guppies. The other thing I learned is less is best. While my 20G is not overstocked, I have a 15G with a divider, 2 bettas, some nerite snails and 3 otocinclus on each side. That tank is so pristine, and cleaning it is so easy. Water is always crystal clear and it’s a very healthy tank. Plans for my 55G are 10-15 male guppies, 5-6 Cory cats, 5-6 otocinclus, some colorful mystery snails, and the very last to be added – 5 female bettas, with lots of plants. My female guppies will remain in the current 20G, and I have 2 5G fry tanks. I’m also finding that when I turn the lights on in the morning, all my fish freak out. It can’t be good for the albinos. So for my 55G I bought lights that simulate sunrise, daytime, twilight, and nighttime, all programmable. Yes, it’s more expensive but I think it’s more natural and they won’t freak out with daytime mode. Thanks for all your help,! I’m sure I’ll be asking more questions from time to time.

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