How Long Can Fish Live Without A Filter

How Long Can Fish Live Without A Filter

In nature, fish live without a filter their whole lives. However, natural waters get churned up by weather and streams and other things you don’t have in a home aquarium.

To adjust for this, we use filters and pumps to move the water, keep it clean and add oxygen for the fish to breathe. How long can a fish live without a filter?

Fish can live almost two days without a filter if their tank is large enough and you change the water and aerate it regularly. Fish will suffocate from lack of oxygen in stagnant tank water. Fortunately, you can help keep your fish alive temporarily by swapping out half the water every couple of days.

How Many Hours Can Fish Live Without A Filter

Most species of fish can live about 48 hours without a filter. However, it will not be an easy or comfortable two days as they slowly run out of oxygen and suffocate.

Ideally, your fish should only be without a filter running during tank changes, which are typically brief.

When you turn off the filter, new oxygen stops cycling in, and any automatic cleaning ceases. While it will take longer for the mess to build up than for the oxygen to deplete, it will begin almost immediately.

So, in addition to the air running out, the fishes’ tank is also becoming dirtier. Naturally, this is very traumatic to the fish after just a few hours.

Pro Tip: Not all fish are created equal. Some species can survive in fishbowls with no filter. However, in general, a fish that needs a filtered tank won’t make it very long without that filter.

Can Fish Survive Overnight Without A Filter

A fish can survive overnight without a filter. If your power cuts out for a few hours, the fish will start to lose its oxygen supply.

Some species, like bettas, tend to head toward the surface to breathe, and they may survive longer because a bit of oxygen is more available.

However, bottom feeders like catfish will run low on O2 sooner, especially if they are already low energy and aren’t churning up the water by moving a lot.

Can Fish Survive Without A Filter For A Day

Most species of fish will survive for a day without a filter. However, the size of their tank impacts their survival rate significantly.

In short, more water carries more oxygen. Additionally, it also depends on how many fish there are in the tank because ten fish will need ten times the O2 of a single fish.

How Long Can My Fish Live Without A Filter

Depending on the species, your fish can live without a filter for a couple of days or its entire lifetime. It is essential to understand what type of habitat your fish requires.

However, it would be best always to assume that an aquarium fish couldn’t make it long without their filter unless you are a hundred percent certain they don’t need it.

How Long Can A Fish Live In A Bowl Without A Filter

Fish that live in bowls instead of aquariums can live their entire lives without a filter. It is vital to only do this with species that can survive bowl life.

Moreover, they need very regular bowl cleaning, and it helps to plant water-dwelling plants inside to help keep up the oxygen levels.

According to, “If you select a bowl that is tapered at the top, don’t fill it all the way. Without a filter, there needs to be plenty of surface area at the top of the waterline so that the (fish) are able to get enough air.”

How Long Can Aquarium Fish Live Without A Filter

Aquarium fish will typically consume the oxygen at lower levels of their tank first. After that, they will go toward the surface, where more oxygen is available if the filter is off or missing.

Sadly, this is very hard on the fish, and most species only live a day or two without a filter before they perish from lack of O2 to breathe.

However, this only applies to a single fish in an aquarium well suited to its size and species. If your aquarium has multiple fish, it will take less time to run out of oxygen.

The worst case is an overcrowded tank where fish can suffocate even when the filter runs due to competition and limited resources.

If you have a lot of fish in your aquarium and they seem to try to hang out near the filter, they may be having trouble getting a breath.

How Long Can Goldfish Live Without A Filter

Goldfish don’t need a filter. Instead, they need space and a wide-open mouth to their bowl. The natural oxygen that comes from a large surface area is enough for these decorative fish.

Most people think of this species as small and hard to care for because goldfish frequently die when kept in plastic bags for transport. There’s no air in those bags.

A properly cared for goldfish will thrive and grow larger than you expect, and it will need a much bigger space.

According to Live Science, “When they are kept as pets in small fish tanks and aquariums, goldfish tend to stay about 1-2 inches long and never grow larger than 6 inches (15 centimeters), according to the DEC. However, in the wild, goldfish often reach 12 to 14 inches (30 to 35 cm) in length. The largest pet goldfish was 15 inches (38 cm) long, 5 inches (12 cm) wide, and weighed over 2 lbs (0.9 kg).”

How Long Can A Betta Fish Live Without A Filter

Betta fish can live without a filter. In fact, most bowls and tanks less than two and a half gallons typically lack a filter.

However, a betta fish needs a much larger space than those tiny cups they’re sold in when you find them in stores.

That said, you should put solo betta fish in a 3 gallon or larger filtered tank without other fish since they are aggressive.

How Long Can Tropical Fish Live Without A Filter

Tropical fish tend to have more requirements than other fish, like warmer water. Notably, a tank set up with living plants, which are often favored for tropical fish habitats, will have more available oxygen, though they still need filters.

Without a filter, they should be alright for a day or two at most. Unfortunately, these types can only last 3 to 12 hours without power due to their heat requirements, so the filter isn’t your only concern if you have warm water-loving pets.

How Long Can Baby Fish Go Without A Filter

Baby is not a species of fish. It refers to their relative age. A baby fish can go without a filter as long as other members of its species.

For example, a baby goldfish is fine with no filter at all, but a baby tropical fish might only last a few hours longer than an adult because it breathes smaller amounts of O2 at a time.

How Long Can Molly Fish Live Without A Filter

Molly fish are relatively typical of aquarium dwellers. A molly fish can survive about two days without a filter to break up the surface tension on the water.

The churning motion is what helps keep oxygen cycling into the tank for your fish to breathe.

How Long Can Koi Fish Live Without A Filter

Koi are closely read to goldfish, and they don’t need a filter. Enough exposed surface area on their water is all this beloved decorative species needs to breathe.

In the wild, carp like goldfish can thrive in natural ponds and lakes, unlike species that require more actively churning waters.

Helpful Tips To Know About How Long Fish Can Live Without A Filter

Any fish can live without a filter, but that life will be short, stressful, and likely painful. Without additional oxygen, a small tank will quickly become a watery grave within 2 to 3 days at most without intervention.

Below I’ve listed some helpful tips to know about how long fish can live without a filter.

  • If something happens to your filter, your aquarium fish can make it a few hours or a day. However, you can keep them going a lot longer by switching out half the water in their tank daily. This method should only be used as a temporary fix while you acquire a new filter.
  • Another option for manual tank aeration is to move the water yourself. It would help if you were careful not to hurt the fish with this trick, and keep in mind it will also be stressful to fish who are used to having a standard filter. Grab a pitcher or large cup, and carefully scoop up some of the water. You need to hold the container up a few inches and pour it back in so the water mixes. Repeat this a few dozen times at least two to six times a day to give your pet life-saving oxygen.
  • If you’re worried about filters and power where you live, choose a species of fish that doesn’t need so much aeration. Options like guppies, zebra danios, and pea puffer fish are good options. However, it’s essential to ensure these species have a large bowl or tank with lots of water surface exposed to keep them healthy. If you must keep them in a narrow-mouthed bowl, don’t fill it all the way up. Doing this will leave a nice gap at the top for more air to come in contact with the water.

Final Thoughts

Whether a fish in a home tank survives without a filter depends on your dedication. You can swap out the water manually to keep your pets alive when you don’t have a filter to keep the oxygen levels up.

It’s a waste of water and time-consuming, but worth the trouble if you’re waiting on a replacement. Plus, you’ll need to clean the tank more frequently to keep your fish healthy, but it is achievable.

However, I strongly recommend getting a new filter as quickly as possible to save your fish the added stress, leading to health problems.

Ted Smith

My name is Ted Smith and I’m the creator of I have a passion for educating people about animals and wildlife. I have been working with the National Wildlife Federation for the past 10 years and I became a wildlife blogger to help people become excited about animals and encouraged to care for these wonderful creatures.

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