Can Guppies Survive without Filter?

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One of the things to consider when setting up a guppy fish tank is whether to set it up with or without a filter.

Filters are extremely useful for maintaining water clarity and cleanliness. But can guppies survive without a filter or should you add one to their fish tank?

Whenever I’m asked this question by a beginner, I always argue in favor of getting a filter, it just makes things easier.

But in the hands of experienced aquarists, guppies can survive without a filter if the right water conditions are otherwise maintained.

So, how can guppy fish survive without a filter? And what does it mean to set up you guppy fish tank without a filter?

Setting Up Your Guppy Fish Tank Without Filter

When putting together a guppy fish tank that doesn’t include a filter, there are a few things that you should be very careful about.

– Cycle Your Aquarium Without Fish

Carrying out the nitrogen cycle for your aquarium is one of the most important things you can do to create a balanced ecosystem for your guppies.

The purpose of the nitrogen cycle is to populate the aquarium with beneficial bacteria that feeds on and transform toxins into less harmful components.

While the nitrogen cycle on its own is not enough to maintain a healthy ecosystem, it’s a crucial part of a series of aquarium maintenance-related tasks that together will ensure that the gentle water chemistry isn’t out of balance.

Performing the nitrogen cycle isn’t difficult per se, but it does take some patience and time.

First off, while you’re performing the nitrogen cycle, there shouldn’t be any fish in your aquarium.

In the absence of beneficial bacteria that can neutralize toxins, your fish will end up suffocating on their own waste product.

I advise you to read up on the nitrogen cycle and carry it out to its full completion to get the best results. Your guppies will be grateful if you commit to doing the nitrogen cycle naturally.

Here’s a quick starter on the steps involved in the nitrogen cycle:

  • Add unchlorinated freshwater to the aquarium;
  • Add small amounts of flake foods daily to the aquarium until you can detect a spike in ammonia;
  • Continue adding small amounts of flake foods daily and start monitoring for nitrites;
  • Ammonia levels start to decrease as nitrites start to appear because of the bacteria that feed on ammonia, transforming it into nitrite;
  • Once ammonia and nitrite levels plummet, nitrates should start appearing thanks to the colony of bacteria that feed on nitrites;
  • At 0 ppm ammonia and 0 ppm nitrites, your nitrogen cycle is completed.

Nitrates aren’t completely harmless for your guppies, but they’re far less dangerous. To keep nitrates in check — along with ammonia and nitrites — you should focus on regular tank maintenance.

Changing the water weekly or biweekly at a 20-50% rate, scooping out uneaten food and decaying plants, and siphoning the substrate are some of the ways to control the water chemistry.

An aquarium filter is an extra layer of protection on top of all these tasks, but they may not always be necessary as there are a few other ways to make sure your guppies will survive even without a filter.

– Use Lots of Live Plants

Beyond looking lovely in your aquarium, being a food source for guppy fish and fry, and offering them cover, live aquatic plants also double as an all-natural filter system.

They feed on the toxins released by waste products and drive oxygen into the water. They also help speed up the nitrogen cycle if you decide to add them as soon as you set up the aquarium.

Live plants will also limit algae growth by competing with them for resources. Besides driving oxygen into the water, they’ll also drive oxygen into the substrate preventing aquarium substrate gases that form in anaerobic environments.

To achieve best results, you need more than a few plants placed sporadically in your aquarium. The exact number depends on how large your aquarium is and how many fish you’re housing.

Some good live aquarium plants to consider are anubias nana, crypt wendtii, micro sword, pygmy chain sword, java moss, java fern, hornwort, and Amazon sword.

Be advised that some plants need dosing with fertilizers, which can also throw off the water chemistry, so choose plants that are low-maintenance and don’t require dosing with fertilizers.

– Regular Aquarium Maintenance

Aquarium maintenance is crucial even when you have a filter installed. In the absence of a filter it becomes even more important.

I already mentioned that weekly or biweekly water changes coupled with aquarium cleaning are part of the routine maintenance of any freshwater aquarium.

Without a filter, however, you may need to perform more frequent water changes as weekly or biweekly changes may not be enough.

Monitoring toxin levels in the aquarium will tell you how often you need to perform water changes and at which rate.

I recommend starting with weekly 50% water changes to see how the water chemistry is, and adjust to more frequent changes as needed.

It takes a bit of experimenting, but if you find yourself needing to make water changes every day or every other day, it’s best if you invest in an aquarium filter.

When doing water changes, do make sure to use a water conditioner if you’re going to use tap water to neutralize chlorine.

Chlorine and other tap water disinfectant agents can easily kill of bacterial colonies in your aquarium and will irritate your fish as well.

– Choosing the Right Substrate

Guppy fish aren’t fussy about their substrate but when you’re setting up a filterless guppy aquarium, the substrate becomes another aspect you must carefully consider.

Since you’re going to have plants in the aquarium, you need a substrate that has a good nutrient-holding capacity. Plus, it has to be an easy-to-clean substrate.

Sand is, therefore, out of the question. It has no nutrient-holding capacity and it’s more difficult to clean compared to other substrates. Gravel isn’t much better either at holding nutrients.

I recommend an all-in-one aquarium substrate like ADA Aqua Soil, which comes pre-loaded with nutrients and it can sustain plant life.

– Choosing the Right Aquarium Size

A small aquarium is difficult to maintain even with a filter around. I recommend starting with a larger aquarium as a bigger aquarium and higher water volume is more stable.

In a small aquarium, the water chemistry is easily disturbed and difficult to restore. Ammonia spikes due to increased waste are more likely to happen in a smaller aquarium.

So which aquarium size is right? It depends on how many guppies you’re planning on keeping, but in no scenario should you go below 10 gallons. In fact, it’s best to aim bigger.

How Many Guppies per Gallon?

The general rule of stocking your aquarium with guppy fish is calculating 1 gallon of water for 1 inch of fish. This is the general rule for a typical guppy aquarium.

But your filterless guppy aquarium won’t be a typical one, so while you could add up to 9-10 guppies to a 10 gallon aquarium, you should add less to a filterless guppy fish tank.

Even in a regular 10-gallon tank, 10 guppies are a stretch considering that aquarium equipment and live plants also take up place, preventing your fish tank from holding 10 gallons of water.

Start with a smaller batch of fish to see how you can maintain their water conditions. As you become more experienced, you can add more guppies.

Overstocking the aquarium can cause all sorts of trouble from increased toxin levels to depleted oxygen levels, all of which can cause illness and death.

Is an Air Pump Needed?

An air pump has the role of moving the water in the aquarium, so that it breaks the surface of the water, allowing oxygen exchange to work.

Beyond the lack of enough oxygen, another problem that can arise with an aquarium without water movement is surface scum, which is a white film that forms on the top of the tank.

Water movement will help drive more oxygen into the water and will prevent the formation of the white filmsy scum on the top of the aquarium. I recommend having an air pump in your guppy fish tank.


It’s not impossible to set up a filterless guppy fish tank, but it’s not something I would recommend for a beginner as it requires some expertise.

It takes a lot of tweaking and if you’re inexperienced, you can easily misjudge things and harm your fish in the process.

There’s a reason why nearly all fish aquarium guides recommend using an aquarium filter. While technically it is possible for guppies to survive without a filter, it’s best if you have a filter system installed in your aquarium.

If you do set up a filterless guppy aquarium, make sure to properly cycle your aquarium, add lots of live plants, monitor the water chemistry, don’t overstock the aquarium, and choose the right aquarium size.

Updated: January 9, 2022
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