10 Fish For Small Aquarium with Images & Details!

Fish for small aquariums are gaining more and more popularity every year. Small aquarium refers to the size of the aquarium whose volume does not exceed 40 liters (and usually even less).

These small-aquariums have several advantages like they do not take up much space, they are easy to fit into any interior, and maintenance is fast enough, not to mention saving water, conditioning, and feed.

The main difficulty in keeping small aquariums is their instability, As it is much easier to upset the biological balance in them than in larger aquariums. Although modern preparations and equipment can help you up at this point.

Unfortunately, not all aquatic inhabitants can be kept in such small aquariums; for this, only species no larger than 5 cm can be used.

In our today’s article, we will cover the top 10 fish that are perfect for keeping in a small aquarium.

Endlers Guppy Fish

The younger brother of the world-famous guppy fish has also become a real find for lovers of small-aquariums. The small body size (up to 3.5 cm) allows you to keep Endler guppies in aquariums with a volume of 30-40 liters.

Brightly colored males will become real decorations. With all this, Endler’s guppy is also a viviparous species, which means the complete absence of problems with obtaining the offsprings.

Fish get along well with any proportionate species. But it’s better not to keep them with ordinary guppies because representatives of these two related groups can interbreed.

Sparkling Gourami

Sparkling gourami is much less common than its closest relatives, which is primarily due to the rather inconspicuous color of the fish. However, it is difficult to find a more suitable candidate for keeping in a small aquarium.

Adult sparkling gourami grows up to 4 cm in length. Like other labyrinths, they do not need forced aeration, because fish are able to absorb atmospheric air. Sparkling gouramis are best kept in a species aquarium.

Minnow Fish

Minnow fish have been known to aquarists for a long time. The first copies fell into the hands of lovers more than 80 years ago.

In beauty, The minnow fish is no way inferior to their tropical competitors – neon tetras, because they have a bright sparkling strip on their bodies. However, in terms of endurance, Minnow fish will give odds to many aquarium inhabitants.

This fish can tolerate cool water perfectly, get along well with living plants, and will be a good choice for settling in a small aquarium because they do not grow more than 4 cm.

You will have to keep Minnow fish in flocks, but an aquarium of 30 liters will be enough for this purpose and there will be no problems with compatibility if you choose small peaceful species as their tank mates.

Celestial Pearl Danio or Galaxy Rasbora

Galaxy rasbora was discovered in 2016 and due to their small size, They are perfect for keeping in a small aquarium. These tiny inhabitants of the high mountain lakes of Myanmar are a real find for a small volume.

Galaxy rasboras do not only have a small size (the length of an adult rarely reaches 3 cm), but also they have a stunning color like light spots are scattered on the gray-blue body, and the fins have a bright red color.

Many experts who saw photos of the Galaxy rasbora thought that the images are FAKE or photoshopped.

It is necessary to keep this fish in flocks because this fish loves to live in a flock and they will amaze you with their social behavior once they are in a group. Peace-loving fishes are perfect tankmates for minnow fish.


The name of the genus already reflects the miniature size of these aquarium inhabitants, because the Nannostomuses translates as “small mouth”. Indeed, the maximum size of these fish does not exceed 3 cm, which makes them excellent candidates for keeping in small aquariums.

Pencilfish are schooling fish; they must be settled by a group in which a strict hierarchy is built. Mostly fish are active in the evening, but in the afternoon they prefer to drift at the surface of the water.

An interesting feature of pencil fish is a change in body color during the day – at dusk, the fish become lighter.

Pencil fishes are perfectly compatible with small decorative fish species.

Otocinclus Catfish

Even in small aquariums, I would like to see catfish, who are real aquarium assistants. They eat up the rest of the feed and actively destroy the algae.

Unfortunately, most representatives of this group of fish are quite large, and they have to be kept in flocks. But otocinclus catfish is a pleasant exception. This small catfish barely reaches a size of 3 cm, so for its maintenance, you do not need a large aquarium.

Despite its modest size, otocinclus is a real hard worker who actively destroys algae in the aquarium, helping to keep it clean.

Betta Fish

Betta fish can be seen often in small volume tanks. This is due to the fact that these fighting fish belong to the Labyrinth group and they have a special organ (labyrinth) that allows them to use atmospheric air for breathing.

This makes forced aeration in the aquarium unnecessary. However, the presence of a filter is very important even for such hardy fish, so ideally an aquarium for a betta fish should have a volume of at least 20 liters.

Betta fish don’t need any tank mates to stay happy in the aquarium. Two males of betta cannot be kept together; there will be constant skirmishes.

If you want to have females, then there must be at least two female, so that an overly active male sprays his possible aggression.

Forktail Blue-Eye

Forktail Blue-Eye in nature lives exclusively on the island of New Guinea. This small fish grows in length up to 4-5 cm, so for its maintenance, you do not need a large aquarium. Forktail Blue-Eye leads a flocking life; outside the group, the fish experience extreme stress.

Forktail Blue-Eye is colored yellow-green, fins have yellow fringing. The dorsal fin is divided into two parts, and the pectorals are directed upwards. This fish has a blue eye rim that glistens in reflected light.

Forktail Blue-Eye’s beautiful appearance will leave few people amazed! In a suitable volume of the aquarium, Forktail can be kept with small characins or zebrafish without any problems.

Red Neon Blue Eye Rainbowfish

Red Neon Blue Eye Rainbowfish is a miniature aquarium fish with an attractive appearance. In males, the anal and dorsal fins are fan-shaped with numerous dark dots.

The main color of the body is orange, and on the back, there is a shiny blue stripe, like in neon tetras. The iris of the eye is colored in blue, This is the reason they are called ” Red Neon Blue Eye Rainbowfish. The maximum size to which fish can grow is 3.5 cm.

In nature, this species lives only on the island of New Guinea. It is necessary to keep red neon blue eye rainbowfish in flocks. It is possible to combine them with other proportional fish that are close in temperament.

Ember Tetra

A relatively young aquarium species that is perfect for small-sized aquariums. The size of this baby barely reaches 2 cm. However, a flock of ember tetra fish looks extremely impressive, especially in a herbal aquarium.

Perhaps the joint content in a common aquarium with small peaceful species. Having little experience, it is possible to breed these tetras at home.