Fish that Don’t Need a Filter (11 Great Species for Your Fishbowl)

Interested in fish that don’t need a filter? This guide is for you!

Aquatic filters are essential in an aquarium as they help maintain overall tank safety and cleanliness.

By getting rid of dirt and toxins and oxygenating the water, filters improve the lives of your pet fish. This is more so because your fish’s life is compromised without clear and clean water.

But, did you know some aquatic pets don’t need filters? These fish are tough enough to survive in less-than-ideal fishbowl conditions. They include betta fish, white cloud mountain minnow, guppies, and Corydoras catfish.

So, if the tank filter fails for any reason (such as a power blackout), you can be sure these fish are tough enough to survive longer than most.

Characteristics of a Fish Species That Doesn’t Need a Filter

Fish that can survive without a filter are generally hardy. While some require close monitoring, a good number of them will do fine with minimal care.

However, this is not to say that you should neglect your fish just because he is hardy. On the contrary, you need to take good care of your pet fish as a loving pet parent should.

These fish remain healthy without a filter. However, you may have to adjust the aquarium to give this fish an added advantage.

Let’s have a look at these species in detail.

The Top 11 Fish Species That Don’t Need a Filter

#1 – Betta Fish (Betta splendens)

Although betta fish can be delicate in many ways, it can survive very well without a filter for quite some time.

Also known as the Siamese fighting fish, this species requires a medium level of care. It can live for up to 5 years, growing to about 3 inches in size.

This fish is originally from South East Asia. Here, it was kept got public displays of fighting. For example, males would be put in the same tank where they would engage in a bloody duel.

Nowadays, this fish is kept for its beauty and color rather than for fighting.

Betta fish thrives on temperatures between 240 C and 270 C (760 F and 810 F) and a pH range of 6.5 to 7.5.

Bettas are much beloved because of their striking colors and extravagant tails. Different types of bettas display various kinds of tails.

If you have the space and inclination, you may want to keep a few bettas just to appreciate the full range of their color displays and tails.

However, you cannot keep two male bettas in the same tank.

Although male bettas are friendly and accommodating with other tank mates, two males will fight to the death if they find themselves in the same enclosure.

An interesting thing about betta fish is that they can breathe underwater using gills and from the surface air using their labyrinth organ.

This means betta fish do well even in waters with low-oxygen concentrations. For this reason, they will survive reasonably without filters.

To keep this fish happy and healthy, provide him with a protein-based diet. Bettas are carnivorous that thrive on a wide range of meat diets, including insects and insect larvae.

For comfort and safety, you need to house your betta fish in at least a 5-gallon tank. Female bettas can live together in a sorority of 5 as long as the aquarium is big enough.

Never attempt to house male bettas together, as this is a sure recipe for trouble.

Ideal betta tank Mates

  • Neon tetras
  • Feeder Guppies
  • Ghost shrimp
  • Cory Catfish
  • Mystery Snails

Not recommended as tank mates

  • Any colorful fish
  • Fish with flowing tails
  • Killifish
  • Acaras
  • Oscars
  • Parrotfish

#2 – White Cloud Mountain Minnow (Tanichthys albonubes)

This peaceful, easy-maintenance fish can live for up to 7 years. It grows to about 1.5 inches when fully mature.

The white cloud mountain minnow does well in temperatures between 180 C and 220 C (640 F and 720 F) and a pH range of 6.0 to 8.0.

The popularity of this fish arises from its metallic body and red tail, very much like those of neon tetras.

It has shiny, iridescent pink scales interlaced with black stripes running down the length of its body.

The white cloud mountain minnow is a native of China’s Pearl River. In its natural setting, this fish breeds in rice paddies.

This fish is also an outstanding swimmer and prefers to swim along mountain streams. Indeed, this is one of the most active fish you can keep in your home or office aquarium.

The white cloud mountain minnow is an omnivore known to predate on micro worms, algae, and mosquito larvae.

For variety, you can feed a captive white cloud mountain minnow frozen food, dried pellets, alginate pellets, and fresh fruit.

The white cloud mountain minnow enjoys living in a school of about 5 members. Although considered generally peaceful, this fish may become aggressive during mating.

Ideal white cloud mountain minnow tank mates

  • Snails and shrimps
  • Dwarf Gouramis
  • Black Skirt Tetras
  • Water Loaches
  • Zebra Danios

Not recommended as tank mates

  • Killifish
  • Tiger Barb
  • Clown Loach

#3 – Guppy Fish (Poecilia reticulate)

This is a docile, very easy-to-care-for fish with a lifespan of about 2 years. The Guppy varies in size between 0.6 and 2.4 inches.

The water temperature should be kept at 240 C and 280 C (750 F and 820 F) to make this pet fish happy and healthy.

This fish thrives on a pH range of 5.5 to 8.5.

The Guppy is also known as the rainbow fish because of its wide range of dazzling colors. This and their dynamic personality make this fish a good fit for any home or office aquarium.

This freshwater fish is a native of South America. He does well in a heavily-planted tank with adequate hardscapes, such as rocks.

The Guppy appreciates being kept with other guppies. Males display their resplendent colors and wiggle their tails to court the females.

This fish is one of the easiest to care for regarding food and diet. Being an omnivore, it eats a wide range of foods, such as fish flakes, cucumbers, peas, bloodworms, and shrimp.

The best tank mates for this fish are the docile and peaceful kind. Putting the Guppy with an aggressive type of fish will greatly stress it.

Ideal Guppy tank Mates

  • Platies
  • Ghost Shrimp
  • Mollies
  • Gouramis
  • Corydoras

Not recommended as tank mates

  • Tetras
  • Barbs
  • Red-tailed black sharks
  • Aggressive species

#4 – Pygmy Corydoras Catfish (Corydoras pygmaeus)

This is an easy-maintenance, peaceful species with a lifespan of about 3 years. It also goes by the name Pygmy Catfish.

The Pygmy Corydoras thrives in temperatures of 220 C and 260 C (720 F and 790 F) and has a pH range of 6.4 to 7.4.

When fully grown, this fish reaches 1.2 inches in size, head to tail. This means it is small enough to be kept comfortably in a fishbowl.

It may not be very easy to distinguish the coloration of the Pygmy Corydoras because of its small size. However, keeping this 1.2-inch fish is in itself satisfying as you see him swim around the fishbowl.

This fish was widespread in many parts of South America before it made its way to the rest of the world.

In particular, it was commonplace in the Agurico River in Ecuador, the Nanay River in Peru, and the Madeira River in Brazil.

This fish appreciates being kept in a heavily-planted aquarium.

The Pygmy Corydoras can use its intestines to take air from the surface when the tank water becomes too saturated.

This is one of the reasons it can do quite well without a filter.

This species does well in a community of peaceful fish. It would be a mistake to place him with aggressive, bigger fish as this will increase his stress levels.

Being an omnivore, the Pygmy Corydoras thrives on insect larvae, brine shrimp, bloodworms, and fish pellets.

Pick a diet that quickly sinks to the bottom of the tank for this bottom feeder.

To make the Pygmy Corydoras’ life peaceful, pair him with smaller fish. Choosing species that swim on the surface or mid-tank for their tank mates would be best.

Ideal Pygmy Corydoras Tank Mates

  • Neon Tetras
  • Mollies
  • Zebrafish
  • Cherry Barbs
  • Dwarf Gouramis

Not recommended as tanks mates

  • Big, aggressive fish
  • Fish with a mouth wider than an inch

#5 – Sparkling Gourami Fish (Trichopsis pumila)

This easy-to-care-for fish thrives on temperatures between 240 C and 280 C (760 F and 820 F), with a pH range of 6.0 to 7.0.

The Sparkling Gourami is a peaceful fish with a lifespan of about 5 years. When fully grown, this fish can reach 1.5 inches.

Because of their small size, these fish looks like small darts dashing to and fro in the water. They are a sight to behold as they explore the aquarium.

Its long, thin, and beautiful colored bodies make this fish adored by many keepers.

In the wild, the Sparkling Gourami thrives in stagnant, heavily-planted waters. They were initially found in South East Asia, where they survived in some of the harshest waters.

Its hardiness and versatility are also seen in captivity, where it can survive without needing a filter in the tank.

To make this species happy, ensure that you provide him with adequate vegetation in the aquarium. This will give the aquarium a more natural feel, boosting the confidence of this fish.

Additionally, this fish can use the vegetation as shelter whenever the need arises.

Sparkling Gourami’s diet is not complicated. You can keep this fish going for a long time

with adequate supplies of frozen or live insects.

However, you can spice up his diet with other foods because he’s an omnivore. For example, you could use zooplankton, fish flakes, daphnia, veggies flakes, and bloodworms.

The sparkling Gourami can be housed with small, docile fish.

Ideal Sparkling Gourami Tank Mates

  • Neon tetras
  • Dwarf Suckers
  • Dwarf Pencilfish
  • Dwarf Rasboras
  • Dwarf Gouramis

Not recommended as tank mates

  • Black tetras
  • Tiger barbs
  • Male betta fish

#6 – Dwarf Pufferfish (Carinotetraodon travancoricus)

Dwarf Pufferfish

This is an aggressive, medium-care-level species with a lifespan of about 4 years. It grows to 1.4 inches, thrives in temperatures between 220 C and 280 C (720 F and 820 F), and has a pH range of 6.5 to 8.5.

Also known as the Pea Puffer Fish, this species can get highly territorial. As such, you should not keep it with equally aggressive species, such as the betta fish.

Although this fish can get quite feisty, it is a fascinating fish that many keepers find worthwhile to keep in their homes or office fishbowls.

Its aesthetic appeal is further enhanced by its large eyes and brightly colored yellow bellies. This fish is originally from the estuaries and waterways of Southwest India.

In its natural habitat, the dwarf Pufferfish enjoys hanging in areas with heavy vegetation. If you can recreate the same conditions in the aquarium, you’ll make this little fellow very happy indeed.

Also, take care not to create much turbulence in the tank, as this fish will be unable to feed, mate, and breed under such conditions.

The Dwarf Pufferfish needs to be well sheltered to carry out its activities.

Because of their aggressive nature, avoid putting males of this species in the same environment. At times, males are antagonistic to males of other species.

Being a carnivore, the Dwarf Pufferfish thrives on insects, insect larvae, copepods, and algae. They also enjoy a meal of brine shrimp, bloodworms, small shrimp, and algae wafers.

Ideal Dwarf Pufferfish tank mates

  • Filament Barbs
  • Neon Tetras
  • Mosquito Rasboras
  • Ember Tetras
  • Leopard Danios

Not recommended as tanks mates

  • Long-finned guppies
  • Large catfish species

#7 – Paradise Fish (Macropodus opercularis)

This fish belongs to the same family as gouramis and bettas. Species in the anabontoidei family have gills as well as a labyrinth.

This means they can access oxygen underwater as well as from the surface air. As such, they can do quite well in an environment without a filter.

The Paradise fish is a docile species with a lifespan of about 8 years. It can grow to 4 inches in full maturity.

This hardy animal can withstand a wide range of water conditions. It was first imported into Europe as an exotic fish for the aquarium trade.

The beauty in this fish is two-fold – its resplendent colors and hardiness. Both qualities make it a worthwhile fish to keep in your home or office aquarium.

They can tolerate temperatures as low as 180 C (650 F) and are not too particular about the pH levels or water hardiness.

Indeed, this fish can survive quite well without a tank heater. However, it would be best to guard against ammonia buildup, for this is a real threat to the Paradise fish.

#8 – Zebrafish (Danio rerio)

This is an easy-maintenance, docile fish that does well in temperatures of 180 C and 230 C (640 F and 740 F).

It does well in the range of 6.5 to 7.0 pH levels. The Zebrafish has a lifespan of about 5 years, within which time it grows to about 2 inches.

Also known as the Zebra Danio fish, this species is much sought-after because of its breathtaking beauty. It is covered in blue horizontal striped that run the length of its body.

Also, it is a good swimmer, and you’ll enjoy seeing it navigate its way around the tank. Its torpedo-like body moves at mesmerizing speed, further adding to its aesthetic appeal.

The Zebra Dion Fish is originally from India. However, it is today found in a wide range of water from Europe to America and Africa.

Its versatility is seen in its survival in turbulent and calm waters.

This fish species appreciates being kept in a school of more than 5 fish. Their peaceful temperament ensures that they peacefully co-exist in the same tank.

Being an omnivore, the Zebrafish cannot be said to be a picky feeder.

As long as the food is chopped into reasonable pieces, this fish will eat anything from fresh vegetables to fruits and frozen invertebrates.

This species can do well in communities with docile fish. However, the Zebrafish has been known to nip at fish with long fins.

Ideal Zebrafish tank mates

  • Corydoras
  • Barbs
  • Gouramis
  • Swordtails
  • Loaches

Not recommended as tank mates

  • Guppy fish
  • Betta fish
  • Angelfish

#9 – Japanese Rice Fish (Oryzias latipes)

This species has a lifespan of about 4 years, and grows to about 15 inches. The Japanese Rice fish is known for its indefatigability.

It zooms around the aquarium night and day at great speed, only taking a few hours to rest and relax.

This fish was initially found in rice paddies of the South East and Far East Asia. Today, they are found all over the world in home and office aquariums.

One thing about the Japanese Rice Fish is that it likes to be kept in cold aquariums. This is because it is hardier than most other fish and can survive very low temperatures.

As such, it may prove to be quite tricky to get a suitable tank mate for this little critter.

In the wild, the Japanese Rice fish thrives in rice paddies. Here, the waters are shallow and cloudy and don’t have as much oxygen as deeper waters.

Because of this conditioning, this fish can survive quite well without a tank filter.

As it is, cold water is ordinarily richer in oxygen than warm water. This works to the advantage of this fish, as he can survive without additional oxygen for longer.

Actually, the Japanese Rice fish outperforms many tropical fish in this aspect.

#10 – Ember Tetra Fish (Hyphessobrycon amandae)

This is an easy-maintenance species with a lifespan of about 4 years. It grows to a length of 0.8 to 1 inch from head to tail.

The Ember Tetras fish does well in temperatures between 230 C and 290 C (730 F and 840 F) and a pH range of 5.0 to 7.0.

This fish is quite docile and thrives in a community of peaceful, small fish.

The bright orange colors on this fish make this fish a much sought-after attraction in homes and offices.

It provides excellent visual and aesthetic appeal as it moves around the aquarium or fishbowl. However, because of its very small size, it’s not easy to distinguish this fish’s color gradient.

The Ember Tetras thrives in slow-moving waters characterized by thick vegetation. The Araguaia River basin provided this species with the ideal conditions to thrive.

This fish is hardy enough to survive in changing water conditions. Indeed, it can thrive for quite some time without a water filter.

To make your ember tetra happy, you need to provide him with adequate vegetation in the tank. Also, don’t keep him with bigger or more aggressive fish.

This fish thrives on live, frozen, and freeze-dried meals. The ember tetra is particularly fond of brine shrimp and live daphnia.

Being a schooling fish, the ember tetra would appreciate being kept with about 9 or 10 other ember tetras.

Ideal Ember Tetra Tank Mates

  • Other ember tetras
  • Neon tetras
  • Dwarf Gourami
  • Red Cherry Shrimp
  • Pygmy Catfish
  • Small Rasboras

Not recommended as tank mates

  • Any aggressive fish
  • Any fish with a mouth wider than 1 inch

#11 – Freshwater Shrimp (Caridea)

Although the freshwater shrimp is not a fish, we cover it here because it is an ideal tank mate for many of the fishes covered above.

Most freshwater shrimp live for about 1 to 12 years, within which they grow to about 1 to 10 inches.

Some good examples of shrimps you can introduce into the tank to keep your fish company include Amano shrimps, Cherry shrimps, and Ghost shrimps.

These shrimps are unlikely to upset the order of things in the tank. Instead, they are amiable characters, undemanding, and will not get in the way of your pet fish.

At the same time, these shrimps will clean the fish tank of dangerous algae and harmful bacteria.

Some shrimps can survive for some time without a filter. As such, these shrimps will still be good companions to your pet fish in case of a power blackout.

However, it is noteworthy that shrimps cannot survive without oxygen for as long as the fishes we’ve covered above.

Some freshwater shrimp dash to the surface of the water to access surface oxygen before oxygen is restored in the water.

Like fish, shrimps are sensitive to ammonia, nitrates, and nitrites in the water. As such, care must be taken to change the water daily in the absence of a filter.

How to Care for Fish That Don’t Need a Filter

Choose Hardy Cold Water Fish

A tank filter ensures that the water parameters don’t keep fluctuating. Without a filter, you can expect these conditions to change frequently.

You need to select hardy residents for an unfiltered tank. This is one way to ensure the tank inhabitants don’t suffer high casualties.

Cold-water fish species are quite hardy and can survive various wild changes. What’s more, cold water holds oxygen more readily than warm water.

This means your cold-water fish will not have to struggle much to access oxygen. All the same, you have to change about 50% of the water regularly.

Choose the Right Tank Design

From the word go, you should have success on your mind when setting up an unfiltered fish tank. This entails choosing a tank design that provides as much oxygen as possible.

One way to do this is by choosing a design with a large surface area. The larger the surface area, the more oxygen the tank will absorb.

Also, a large surface area allows carbon dioxide to escape from the tank.

Use Oxygen-Producing Vegetation

Most fish that don’t need a filter do well in a vegetative environment. This is because the right plants introduce oxygen into the water and absorb carbon dioxide.

Even without a filter, they allow your fish to get an ample oxygen supply.

The fish and the plants will be in a symbiotic relationship. For example, plants use the nitrogenous matter produced by fish.

Conversely, the fish use the oxygen produced by the plants. In addition, plants are a refuge for fish whenever needed.

Here are a few plants you can consider for your unfiltered fish tank: Anubias, Coontail, Moneywort, green hygrophila, Aldrovanda vesiculosa, Sunset Hygro, Java Moss, and Sagittaria subulata.

Others include Rotala indica, Java Fern, and Villisneria.

Change the Water Frequently

One thing about an unfiltered fish tank is that the water conditions change very fast. The water gets dirty a lot more quickly than in filtered tanks.

To rectify this situation, change about 30 to 50% of the water every 4 days. Although this may seem a tall order, it is the right thing to do.

Use a Proper Substrate Base

Tank filters do more than regulate the oxygen in the water. They also act as breeding grounds for useful bacteria.

You may lose this benefit by using an unfiltered tank. However, you can circumvent this problem by using a well-established substrate base.

The right substrate –especially one that uses a layer of aquatic plants – creates the right conditions for bacterial growth.

Use a Sponger Filter

Some aquarists avoid filters because they are too bulky for the tank or fishbowl. If this defines you, try substituting a filter with a sponge filter.

This substitute will circulate and oxygenate the water. It will also balance nitrate levels in the bowl and allow for the growth of good bacteria.


With a few adjustments, you can effectively manage the environment of fish that don’t need a filter. However, some keepers consider this a challenge and opt for unfiltered tanks.

Others are forced by circumstances to up their skills in managing unfiltered tanks. For example, this may happen in case of a power blackout or if the filter breaks down.

Either way, you won’t have a hard time if you keep the resilient fish species we’ve covered in this post.

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