Do Guppies Need A Filter to Survive?

Guppies are highly adaptable to different water parameters, which makes them a great choice for new aquarium hobbyists. The traditional set-up for a guppy aquarium is simple enough, and with the right equipment on hand, maintenance is just as easy. However, what if you want to do things a little differently? Many people ask me about keeping guppies without a filter.

Can Guppies Survive Without a Filter?

Guppies can survive and live healthy lives even without a filter, but you’re going to have to change some things in your setup and fish tank maintenance routine. Aquarium filters do a lot of the hard work keeping the water clean and reducing maintenance needs.

So, let’s see how you can make it work.

How To Keep Guppies Without A Filter?

Filters work to keep the water clean of impurities and harmful chemicals like ammonia and nitrites. When these build up in the water, the pH level drops and acidity rises. Under such water parameters, fish often get painful burns.  As the levels of these compounds accumulate in their bodies, guppies are no longer able to metabolize food properly.

Eventually, when they reach high toxicity levels, the fish begin to die off. The even worse news is that these compounds can build up rather quickly and you may not know until it’s too late. Needless to say, you must be very mindful about keeping high water quality. Without a filter, you’ll have to take extra safety precautions when setting up and maintaining your aquarium.

Every additional step you take to improve and maintain stable water parameters will further reduce the chances of hazardous waste by-products hurting your fish. Here are some of the best and safest strategies to keep guppies without a filter.

– Complete The Nitrogen Cycle

One of the most important things you can do to set up a safe filter-free aquarium is to cycle your tank before introducing any fish. This is a crucial step in creating a balanced aquarium ecosystem. The nitrogen cycle is the process through which you populate your aquarium with colonies of beneficial bacteria. These bacteria keep the water toxicity down by converting harmful by-products into less dangerous compounds.

You must be patient when going through this first step. Cycling your aquarium isn’t difficult, but it does require time. It’s a delicate process, and you must closely follow the instructions when going through with it. For best results, don’t introduce your guppies to the aquarium until you’re sure that the nitrogen cycle is complete!

There are many comprehensive guides out there on how to cycle your aquarium. I suggest you check them out to form a comprehensive view of the process. However, I’m going to give you a quick run-down of the steps you must take, all in chronological order:

  • Fill the aquarium with fresh, unchlorinated water.
  • Throw in a small amount of fish food every day and wait until ammonia levels begin to rise.
  • Keep adding small amounts of food to the aquarium until you notice a spike in nitrite levels.
  • When nitrites reach significant levels, that means that bacterial colonies have started to grow. These bacteria take the harmful ammonia and transform it into less harmful nitrites.
  • Eventually, ammonia and nitrite levels should drop, and nitrate levels will rise. That means that the bacteria feeding on nitrates have also started to grow. These strains take the leftover nitrites and transform them into safer nitrates.
  • When ammonia and nitrates drop to 0 ppm levels, the aquarium is fully cycled and ready for your guppies to inhabit.

Nitrates are a lot safer for your guppies, but they aren’t completely harmless. You’ll still have to keep the nitrate levels in check. To do that, you’ll need to monitor levels and complete frequent water changes.

For maintenance, I suggest a 20-50% volume water change either weekly or every two weeks. You’ll also have to remove any food leftovers, fish waste, and dead plant matter from the tank, as well as thoroughly cleaning the substrate.

– Perform Frequent Water Changes

We’ve already touched on this one in the previous tip, but I have to stress this point again. Without a filter, you need to keep on top of the aquarium hygiene. Depending on the water volume and how many guppies you keep, you might get away with weekly water changes, but you might still want to be cautious.

More frequent water changes would be even better, as they’d reduce toxin buildup risks even further. You should begin with a weekly water change of 50% and see how things are going. Keep monitoring nitrate and ammonia levels, and adjust from there. If you notice spikes in toxin levels before the next weekly water change, increase the frequency.

Always ensure that the replacement water is dechlorinated because chlorine can kill the beneficial bacteria in the tank. A water conditioner is a safe and effective option to get fish-safe, bacteria-friendly water for your aquarium.

– Use An Appropriately-Sized Aquarium

Tiny tanks are all the rage, but if you plan to operate without a filter, you’ll need to size up your aquarium. The thing about small aquariums is that they’re very hard to maintain even with a filter to do half of the work. When you have a low water volume, waste builds up a lot quicker, and bacteria can’t keep up with the big spikes in ammonia.

Not only that, but small water volumes also mean unstable water parameters in other ways, including temperature and pH levels. For easier control and more stable water quality, I don’t recommend any tank smaller than 10 gallons. But even bigger is better! The ideal tank dimensions and capacity will depend on the number of guppies you want to keep, which brings me to my next point…

– Don’t Keep Too Many Guppies in Your Tank

The more guppies you keep together, the more leftovers and the higher the waste. This leads to sharp increases in toxins, as well as suboptimal oxygen levels. Too many guppies per gallon also make water parameters difficult to manage. So, “How many is too many?”, you might ask. As a general rule, most people advise keeping 1 guppy for every 1 gallon of water at most. So, in a 10-gallon aquarium, you’ll be able to keep 10 guppies.

But remember this applies to filtered aquariums. And this might still be a bit of a stretch because even in a filtered aquarium, guppies don’t enjoy the full tank space. There are also other things taking up room, including the substrate, plants, decorations, and some tank equipment. But in a filter-free setting, 1 guppy per gallon of water might be even more of a stretch.

To maintain stable water parameters, you want to avoid overpopulating your aquarium. I recommend starting with a lower number of guppies, maybe 1 guppy for every 3 gallons of water. Monitor water toxin levels and see how easy or difficult it is to manage this number of fish. You can always add more guppies, but you want to start slow.

– Add Some Live Plants

Aquarium plants do a lot more than just looking aesthetically pleasing. They can also work as a natural filter. They take harmful waste by-products from the water and convert them into oxygen. They keep the substrate healthy and prevent the formation of harmful gases. They also help with the nitrogen cycle and inhibit algae growth.

And the benefits of live aquarium plants don’t stop there! They serve as a hiding spot for your guppies, contributing to a low-stress environment. And they double as a healthy snack, so there’s that too. And think about it, these plants don’t even need frequent watering for obvious reasons. You won’t have to worry about maintaining them once you add them to the aquarium.

But you’ll need a whole lot of them for the best filtration results. How many plants you have to add depends on the tank size and the number of fish you keep. If your aquarium looks like a little forest, that’s probably enough plants. Just make sure you don’t take up too much of your guppies’ space.

Be careful when choosing the plants for your aquarium. Some plants require fertilizers, which might negatively impact water quality. Opt for plants that grow well without fertilizers. Some great options include the micro sword, pygmy chain sword, Amazon sword, hornwort, java moss, java fern, and the Anubis nana.

– Use A Suitable Substrate

Guppies do well with almost any type of substrate. Still, you’ll have to find a nutrient-rich substrate to support plant growth. To make your aquarium maintenance easier, you should also opt for an easy-to-clean substrate. Definitely don’t pick a substrate that you’ll have to change after every cleaning.

My top pick is the ADA Aqua Soil, or any other similar all-in-one substrate. Choose any nutrient-rich, natural, soil-type substrate, as these are the best for growing plants and maintaining healthy bacterial colonies.

– Invest In an Air Pump

An air pump makes it easier to maintain optimal oxygen levels in the aquarium. You might not need one, particularly if you have a smaller-sized aquarium, or if you have plenty of aquarium plants. Still, there is one important benefit beyond water oxygenation.

Because air pumps currents create water movement, they also help to keep the water surface clean. With this constant water agitation, you’re also less likely to get the unpleasant white film buildup on the water surface. Due to this, I’d still recommend investing in an air pump even if you can maintain optimal oxygen levels otherwise.


You definitely can successfully set up a filterless guppy aquarium. However, it’s still not something I’d recommend, because it’s a tedious process that requires a lot of tweaking and experience. However, if you must have a filterless aquarium, I strongly urge you to follow the tips I have included in this article. Filters hugely help you when it comes to maintenance and water quality.

If you want to forego the aquarium filter, you have to combine multiple methods to get the same results. You can’t pick and choose which of these precautions to take. For optimal results, you must do it all— cycling your aquarium, choosing the proper tank, substrate, keeping the guppy population to a minimum, adding in live plants, and completing at least weekly water changes and cleanings.

avatar Noah
I’m Noah, chief editor at VIVO Pets and the proud owner of a playful, energetic husky (Max). I’ve been a volunteer at Rex Animal Rescue for over 2 years. I love learning and writing about different animals that can be kept as pets. read more...

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