Can Guppies and Swordtails Live Together?

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Guppies and swordtails. Two of the most iconic tank fish available. They are affordable, breed in captivity, are handsome, and get along with most other fish, no matter the species they belong to. They even belong to the same Poeciliidae family.

But will these two species make for compatible tank mates? There are several aspects worth discussing here which, hopefully, will shed some much-needed light on the matter.

Do Guppies and Swordtails Get Along?

It depends. Both species are rather friendly and peaceful, and they make for great additions to any community tank. The problems I’m seeing in this sense can be separated into 3 different categories:

– The Need for Space

Guppies and swordtails can easily coexist with each other and other fish species, provided they have sufficient space available. Guppies, for instance, require around 2 gallons of water per fish to remain comfortable in their environment. This is the average requirement for a 2.5-inch guppy.

Swordtails, on the other hand, can grow double that in size. At 5.5 inches, a swordtail will need around 15 gallons of water per fish. If you overcrowd the 2 species, conflict may arise soon, since both species’ males can become quite territorial at times, especially when crowded.

At the same time, crowded tanks cause fish stress, increasing their aggression and lowering their immune system with time. So, they definitely need adequate space to remain comfortable and acceptant towards one another in the long term.

– Tank Setup

How the tank is set up is also key for ensuring the 2 species’ comfort in the long term. Since guppies are smaller, they might become the target of bullying from other, larger fish. This may soon devolve into stress and injuries, prone to infections and parasites.

To prevent this unfortunate scenario, you need to ornate the tank with plenty of plants and decorations. These will contribute to creating a more natural-looking environment and provide the fish with much-needed hiding spots for when they feel stressed out.

It’s a great strategy to break line of sight between fish and create safe spaces where they can retreat when feeling uneasy.

– Mating-Related Aggression

Every fish species’ male will display mating-related aggression. Guppies and swordtails share this aggression when females are available for mating, which is every month. This will cause males to become more violent towards one another, which will also lead to physicality between the 2 species.

Males tend to become more territorial, poke at males and females around them, and become more energetic and fidgety. At this point, they require space, vegetation, and plenty of hiding spots to diminish their aggression and calm the situation.

If you can handle these 3 things right, there’s no reason for guppies and swordtails not to get along with each other. But, as we will see in the following section, these are not the only factors that matter.

It’s also important to consider the 2 species’ environmental requirements and habitat conditions. So, let’s dive into that!

Keeping Guppies with Swordtails

When creating a community tank, the first thing to concern you should be crafting an environment accommodating to all species. This refers to setting aspects like:

– Tank Size

As I’ve already explained, the tank’s size is key to ensuring the fish’s comfort and promoting a stable and clean environment. Combining a small tank with too many fish can only result in overcrowding which will cause a variety of problems along the way. These include:

  • Fish stress – Your fish will experience stress and higher levels of aggression due to constantly bumping into each other. As a result, the violence between the tank inhabitants will increase significantly, leading to injuries, infections, and stress-related diseases.
  • Ammonia boost – Ammonia and nitrites are deadly chemicals that arise due to excess fish waste and decaying matter. Too many fish into a too-tight space will cause a lot of poop. The excess poop will dissolve in the water and change its chemistry for the worse. At this point, not even a filtering system won’t be able to manage the situation.
  • Triggering innate aggression – Some fish species are slightly more aggressive and territorial than others. Forcing them into a tight space will activate their aggressive side, leading to bullying and constant fighting. Smaller specimens will always suffer the most in this scenario.

To prevent these problems, consider investing into a later aquarium. How much space your fish need depends on the species and the fish’s size. A regular guppy requires at least 2 gallons of water, so a batch of 5 guppies can manage themselves in a 10-gallon tank.

The problem is that swordtails need around 15 gallons of water per specimen. Each swordtail you add to the equation comes with extra 15 gallons of water to the total. Do the math, figure out the necessary tank requirements, and invest in a larger aquarium to keep the fish comfortable and healthy.

– Water Temperature

Both guppies and swordtails are tropical fish, which means they typically need the same water temperature. Guppies are more comfortable at temperatures between 72 to 82 F, while swordtails settle for temperatures around 72 to 79 °F. The difference is pretty much irrelevant.

Just make sure the water temperature doesn’t fluctuate too often, too much, or too sudden. Guppies and swordtails are adaptable fish that can live outside of their comfort zone for quite a while. But they don’t cope too well with sudden parameter changes.

As a plus, you should always keep the water temperature in the golden zone. If the water is too cold, your fish will experience a weakened immune system and fall victim to infections and parasites. If the water is too hot, the fish risk suffocating due to not being enough oxygen in the water anymore.

Stick to the goldilocks zone, and your fish will be fine.

– Diet and Feeding

Both guppies and swordtails require a balanced omnivorous diet, providing them with all the nutrients necessary for a balanced life. Guppies, swordtails, and fish, in general, take around 16 to 24 hours to digest a nutritious meal. Since you will only feed them small amounts of food (as much as they can consume within 1 minute), you can feed them twice per day on average.

Make sure everybody has access to food, so you might want to spread it across the water’s surface. This feeding tactic will prevent food-related competition and aggression and allow all fish to feed properly.

As an important note, don’t feed the fish as much as they want to consume. This will lead to overfeeding since all animals display instinctive greed. It’s not their fault, but the fault of their biology and environmental conditioning. In the wild, fish consume as much food as they can find precisely because food is rather scarce.

That problem no longer exists in captivity, but fish can’t reason, so they will retain their innate greed, which may lead to overfeeding. Stick to a balanced feeding pattern to prevent constipation, ammonia increase due to residual food, and algae bloom due to decaying food on the substrate.

– Water Changes

Water changes are needed to dilute the ammonia and nitrites that may poison your fish’s environment and increase the oxygen levels in the water. I suggest performing regular water changes, at least once a week, depending how many fish you have.

The good news is that if you’ve settled for a golden fish-per-gallon ratio and your fish have plenty of space available, you won’t need to perform too frequent water changes. As a general rule, never change more than 10%, maybe 15% of the water on each occasion.

If you change more than that, you risk diluting the essential minerals in the water, downgrading your fish’s environment.

If your aquarium is on the verge of overcrowding, you can change 20% of the water with each session.

– Number of Fish

How many fish specimens you have of each species and gender is important when discussing the stability of the community. Add too many males and not enough females and you’ll create a recipe for bullying, aggression, and constant tension between all tank inhabitants.

There are 2 things that calm the males, no matter the fish species they belong to: more space and more females.

You should have around 3 females for each male guppy or swordtail as a golden rule. If you plan on creating a more extensive community tank, I would consider 4 females for each male.

You should also decorate the tank with a lot of plants, caves, rocks, and wood to create safe spaces for your fish.

Do Swordtail Fish Eat Baby Guppies?

Most definitely. Swordtails can grow up to 5.5 inches, which is typically double than most female guppies’ maximum size. However it’s not like this matters since smaller fish than that will eat guppy fry, guppies included.

A female guppy can produce up to 200 fry in one sitting, and all of them will rush towards the surface. They tend to remain near the water surface to feed and get adequate lighting, which will make them visible to the entire tank. Adult fish will immediately hunt and eat them as soon as they are born.

To prevent this, either pack the main tank with floating plants that gather at the water’s surface or have the female give birth in a separate tank. The latter option is optimal, as it will allow the fry to grow uninhibited in a safe and stable environment. You can add them back into the main tank once they’ve reached at least 4 weeks of age.


Guppies and swordtails can live together in harmony, so long as you provide them with optimal living conditions. Which, fortunately, it’s easy to do since these species are so similar to one another.

Updated: February 8, 2022
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