15 Best Fish For Your Small Tank You Must Know About

When it comes to choosing the best fish for your small tank, you’re spoilt for choice.

Whether you’ve got a 5 gallon, 10 gallon, or 20 gallon nano tank, it’s easy to get carried away when planning who will be a part of your community.

This guide has been created to make that decision easier for you. I’ve created this list of the absolute best small fish and their key care information so you can make a quick, educated choice.

By the end of this guide, you’ll know exactly which small fish is ideal for your aquarium.

1. Chili Rasbora (Boraras Brigittae)

Chili Rasbora, sometimes called mosquito rasboras, are tiny tropical ray-finned shoaling fish native to Borneo.

Male Chili Rasbora are brightly colored red, with an iridescent black stripe running laterally down its small body. Whereas females have round bellies and lighter color markings in comparison

Only growing up to 0.7inches in length, these tiny nano fish do best in a (minimum) group of 8 in a planted peaceful community tank.

They’re active and cute, one of those schooling fish that are always doing something when you look in the tank. You should keep them in a group of at least

You’ll need a planted tank, at least 5-gallons, and you can provide them with a protein rich diet. Brine shrimp, Daphnia, and tubifex micro worms are all good choices.

  • Common names: Chili Rasboras, Mosquito Rasboras
  • Scientific Name: Boraras brigittae
  • Life Span: 8 Years
  • Size: 0.7 inches (1.9 centimeters)
  • Minimum tank size: 5 gallons
  • Care level: Beginner
  • Temperament: peaceful
  • Temperature: 68°-78°F (20°-25.5°C)
  • pH: 5.0-7.0
  • Diet: carnivore – crushed flake, baby brine shrimp or live or frozen daphnia.

2. Neon Tetra (Paracheirodon innesi)

Blue neon- tetra, freshwater fish in aquarium

One of the most popular small freshwater fish, Neon Tetra, is native to the blackwater and clearwater  Amazon River basin.

Being part of the Characidar family, Neon Tetras are small, thin-bodied fish with small fins and are defined by their neon blue and red color markings.

As a schooling fish, you should keep Neon Tetras in a group of at least six in a 10 gallon planted tank. However, the larger the tank and shoal, the more interesting and active they’ll be.

A great fish for beginners, Neons are hardy, unfussy eaters, and require no specialist equipment.

  • Common names: Neon Tetra, Neon Fish
  • Scientific Name: Paracheirodon innesi
  • Life Span: 10 years
  • Size: 1.5 inches (3 centimeters)
  • Minimum tank size: 10 gallons
  • Care level: Beginner
  • Temperament: Peaceful
  • Temperature: 72°-76°F (22.2°-24.4°C)
  • pH: 6.0-7.0
  • Diet: omnivore – high quality flake food, micro pellets or baby brine shrimp

3. Cardinal Tetras (Paracheirodon Axelrodi)

The cardinal tetra (Paracheirodon axelrodi) is a freshwater fish

Another tiny freshwater nano fish from the Characidae family, the Cardinal Tetra looks very similar to the Neon. However, the Cardinal Tetra grows to 2 inches and has bright ventral parts with iridescent red and blue stripes running the length of its body.

A peaceful shoaling fish, again you want to keep a school of at least 6 in a 15 gallon planted community tank.

They’ll do well with tank mates like, dwarf gouramis, plecos, rasboras, zebra danio, and other tetra species or peaceful tropical fish. You won’t need any special equipment, and can feed an omnivore diet of high-quality fish food.

  • Common names: Cardinal tetra, large neon tetra, red neon, roter neon
  • Scientific Name: Paracheirodon Axelrodi
  • Life Span: 4 Years
  • Size: 2 inches (5 centimeters)
  • Minimum tank size: 15 gallons
  • Care level: Beginner
  • Temperament: peaceful
  • Temperature: 72°-76°F (22.2°-24.4°C)
  • pH: 6.0-7.0
  • Diet: omnivore – high quality flake food, small pellets, brine shrimp and live or frozen daphnia.

4. Bettas (Betta splendens)

Betta fish in a planted aquarium

Betta (siamese fighting fish) are a small tropical fish originating from the tropical waters of Southeast Asia. These tropical fish are known for being fiercely territorial.

There are over 73 varieties of the genus Betta, and are some of the most widely available aquarium fish around the world. This is down to their array of vivid colors, large flowing fins, and intelligence.

Betta fish can learn tricks and have the ability to recognize and greet their owner.

Another great beginner-fish, you’ll want to provide this curious fish with a stimulating environment. A 5-gallon planted tank with plenty of decorations to keep this intelligent fish stimulated will keep it active and healthy.

Males should always be housed alone. While females can be kept in a sorority, however, I would only recommend this for experienced aquarists.

  • Common names: Betta, Siamese fighting fish
  • Scientific Name: Betta splendens
  • Life Span: 2-5 years
  • Size: 2-3 inches (5.7 centimeters)
  • Minimum tank size: 5 gallons
  • Care level: Beginner
  • Temperament: aggressive, males should be kept alone
  • Temperature: 75°-81°F (23.8°-27.2°C)
  • pH: 6.5-7.5
  • Diet: carnivore – Bettas eat mostly insects in the wild so it’s best to feed them things like Fluval Bug Bites Betta Formula, frozen or freeze dried bloodworms or live daphnia.

5. Harlequin Rasboras (Trigonostigma heteromorpha)

The Harlequin Rasboras is a beautiful freshwater fish with a small lozenge-shaped body with a vibrant ruby coloration and black marking shaped like a funnel (known as a “black wedge”), running from their dorsal fins to their tails.

Growing up to 2 inches, these small active shoaling fish should be kept in a group of at least six in a 10 gallon planted tank. Although, keeping them in a larger group in a bigger tank will not only increase their well-being, but also from an aesthetic point of view, a large shoal of harlequin rasboras is truly stunning to witness.

  • Common names: Harlequin Rasboras, Red Rasbora
  • Scientific Name: Trigonostigma heteromorpha
  • Life Span: 6 years
  • Size: 2 inches (5 centimeters)
  • Minimum tank size: 10 gallons
  • Care level: Beginner
  • Temperament: peaceful
  • Temperature: 72°-81°F (22.2°-27.2°C)
  • pH: 6.0-7.5
  • Diet: omnivore – high quality flake foods, live or frozen daphnia and bloodworms.

6. Fancy Guppies (Poecilia Reticulata)

Many guppy fish in aquarium

Fancy guppies have been selectively bred through programs to produce a variety of stunning, bright colors, pattern combinations, and fin shapes and sizes. As a result, these livebearers are now one of the world’s most popular small fish for  freshwater aquariums.

Guppies are a fish that stays small, growing to around 2 inches in length, and are famous for breeding a lot. So they’re best kept in small schools of 5 males or one male per 3-4 females.

If you’re going to house around 5 guppies, a 5-gallon tank will be enough but a 10 gallon would be easier to manage. Guppies love live plants and tropical water parameters.

  • Common names: Fancy guppies, guppy, millionfish, rainbow  fish
  • Scientific Name: Poecilia Reticulata
  • Life Span: 2-3 years
  • Size: 2 inches (5 centimeters)
  • Minimum tank size: 5 gallons
  • Care level: Beginner
  • Temperament: mostly peaceful. Males can sometimes harass females and each other.
  • Temperature: 70°-82°F (21.1°-27.7°C)
  • pH: 7.0-8.0
  • Diet: omnivore – micro pellets, high quality flake food, frozen brine or mysis shrimp.

7. Endler’s Livebearers (Poecilia wingei)

Male black-bar Endler

Endler’s are a small fish native to the Paria Peninsula, Venezuela, and are one of my personal favorite livebearers.

Closely related to guppies (often hybridized with them), male endler’s can have intense color markings of black, orange, and metallic green. And just like guppies, endler’s will breed a lot. So best to be kept in a school of all males or one male per 3-5 females.

These peaceful nano fish will thrive in tropical community tanks, mostly occupying the upper levels of the water column. They require no specialist equipment and will do well on an omnivore diet consistent with high-quality fish food and some live food like bloodworms.

  • Common names: Endler’s Livebearers, Endler’s
  • Scientific Name: Poecilia wingei
  • Life Span: 2-3 years
  • Size: 1-1.8 inches (2.5-4.5 centimeters)
  • Minimum tank size: 5 gallons
  • Care level: Beginner
  • Temperament: peaceful
  • Temperature: 75°-80°F (°-°C)
  • pH: 7.0-8.0
  • Diet: omnivore – micro pellets, flake food, frozen bloodworms and mysis shrimp are good choices.

8. Zebra Danios (Danio Rerio)

Best freshwater fish for beginners Zebra Danios with distinctive horizontal zebra stripes swimming against soft green plants background. Soft focus

Zebra Danios, also known as zebrafish, belong to the Cyrindae family native to South Asia. It’s name comes from the five metallic blue stripes running on the side of its small torpedo-shaped body down to the caudal fin.

When housed in a shoals of at least 5 in a 15 gallon long aquarium, zebra danios will be extremely active and playful fish. These fish are a fun addition to any small tank.

  • Common names: Zebra Danio, Zebrafish, Striped Danio
  • Scientific Name: Danio Rerio
  • Life Span: 5 years
  • Size: 2.5 inches (6.3 centimeters)
  • Minimum tank size: 15 gallons
  • Care level: Beginner
  • Temperament: peaceful
  • Temperature: 65°-77°F (18.3°-25°C)
  • pH: 6.5-7.5
  • Diet: omnivore – high quality flake food, micro pellets, live or frozen daphnia or bloodworms.

9. Bluefin Notho (Nothobranchius Rachovii)

Bluefin notho swimming in planted tank

Bluefin Nothos (Rachovii Killifish) are a type of killifish originating from Mozambique, where they live in tiny bodies of water which dry up every year, killing the adults and leaving only their eggs. Because of this, Bluefin Notho only have a lifespan of 1-2 years.

Despite their short life span, the bluefin notho is a vibrant nano fish full of life and energy. Brightly colored, with metallic blues, deep reds, and stripy fins.

They will do best in a 5 gallon tank with tropical water parameters and lots of live aquarium plants.

  • Common names: Bluefin Notho, Rachovii Killifish
  • Scientific Name: Nothobranchius Rachovii
  • Life Span: 1-2 years
  • Size: 2.4 inches (6 centimeters)
  • Minimum tank size: 5 gallons
  • Care level: Intermediate
  • Temperament: semi-aggressive, especially between males
  • Temperature: 68°-75°F (20°-24°C)
  • pH: 6.0-7.0
  • Diet: predator – frozen and live foods like daphnia, baby brine shrimp, bloodworms and cyclops

10. White Cloud Mountain Minnow (Tanichthys Albonubes)

One of the hardiest species of freshwater and coldwater fish, the small While Cloud Minnow has the ability to adapt and thrive in a wide range of water parameters (45°-70°F).

Growing up to only 2 inches in length, this slim bodied fish can range from a bright golden color to a silvery blue with bright red fins.

They should be kept in a shoal of at least 6 and will often be most active when housed in cooler water temperatures. When cared for properly, they can have a lifespan of up to 5 years or longer. 

  • Common names: White Cloud Minnow, Canton Danio, Chinese Danio, White Cloud, White Cloud Mountain Fish
  • Scientific Name: Tanichthys Albonubes
  • Life Span: 3-5 years
  • Size: 2 inches (5 centimeters)
  • Minimum tank size: 10 gallons
  • Care level: Beginner
  • Temperament: peaceful
  • Temperature: 45°-70°F (7.2°-21.1°C)
  • pH: 6.0-8.0
  • Diet: omnivore – flakes, micro pellets, live and frozen daphnia, baby brine shrimp and bloodworms.

11. Celestial Pearl Danio (Danio margaritatus)

The celestial pearl danio (galaxy rasbora), are small, 1 inch freshwater fish with a dark blue bod covered in golden spots.

This gold color also runs along their backs. Females have bright orange bases on their fins and tails. Males have large patches of red and black on their fins. They are gorgeous.

Not true schooling fish, celestial pearl danios are happier  in groups of one male per 3-4 females. Although primarily a peaceful fish, males can become aggressive over females, so keeping this ratio is key to a happy environment.

  • Common names: Celestial Pearl Danio, Galaxy Rasbora
  • Scientific Name: Danio margaritatus
  • Life Span: 3-5 years
  • Size: 1 inch (2.5 centimeters)
  • Minimum tank size: 10 gallons
  • Care level: Intermediate
  • Temperament: males will fight over mating rights. Provide lots of hiding places.
  • Temperature: 73°-79°F (22.7°-26°C)
  • pH: 6.5-7.5
  • Diet: omnivore – flake food, micro pellets, live and frozen foods.

12. Sparkling Gourami (Trichopsis Pumila)

The sparkling gourami (pygmy gourami) has a laterally compressed body with a deep chest that tapers slightly towards the tail.

Their bodies are grey or beige with bright metallic red and/or blue speckles. Their fins and tail are almost transparent with rows of more metallic speckles. Their eyes are large and metallic looking as well.

A small hardy fish, the sparkling gourami is a great choice for a small aquarium. A heavily planted, 10 gallon aquarium would be perfect for a small group of 3-5. They can do well in peaceful community tanks as long as they don’t have to compete for food with more aggressive fish.

  • Common names: Sparkling Gourami, pygmy gourami
  • Scientific Name: Trichopsis Pumila
  • Life Span: 4-5 years
  • Size: 1.5 inches (3.8 centimeters)
  • Minimum tank size: 10 gallons
  • Care level: Intermediate
  • Temperament: peaceful
  • Temperature: 76°-82°F (24.4°-27.7°C)
  • pH: 6.0-7.0
  • Diet: omnivore. This species does best if given a mix of animal protein and algae-based foods: high quality community flake food, spirulina, micro pellets.

14. Pygmy Corydoras (Corydoras Pygmaeus)

Pygmy corys are adorable tiny catfish that grow up to 1.3 inches. They are active bottom dwellers that have a slightly humped back. Their foreheads are steeply sloped up to the hump at their dorsal fin.

From there, the body tapers down towards the tail. These are great little cleaner fish and frankly, their behavior in a big school is pretty funny. They act like a pack of hyper little kids let loose in a candy store.

Best kept in groups of at least 5 in a ten gallon planted tank. However, a larger group (10 or more)  in a bigger tank would provide much more activity due to them feeling safer in larger numbers.

A peaceful fish, pygmy corys can be kept with other smaller fish species in a community tank. They’ll feed on algae wafers, sinking pellets and love a frozen bloodworm.

  • Common names: Pygmy Corydoras, Pygmy Catfish
  • Scientific Name: Corydoras Pygmaeus
  • Life Span: 3 years
  • Size: 1.3 inches (3 centimeters)
  • Minimum tank size: 10 gallons
  • Care level: Beginner
  • Temperament: peaceful
  • Temperature: 72°-79°F (22°-26°C)
  • pH: 6.4-7.4
  • Diet: omnivore – sinking foods like pellets and wafers. They also love frozen bloodworms and gel foods like Repashy Bottom Scratcher.

15. Otocinclus (Otocinclus Macrospilus)

Otocinclus catfish in planted fish tank

Otocinclus are nano catfish bottom-dwellers famous for their algae consumption. A popular addition to most aquartist clean up crew, Otos are small cute fish that provide plenty of entertainment.

Their look is characterized by their armour plated body and suckermouths, otocinclus will stay small, growing up to 2 inches in length.

They’re easy to care for, and are best kept in schools of at least 5 in a 10 gallon planted tank. However, in the wild they are found in much larger shoals of thousands. So the larger you can do the more active your Otos will be.

Plenty of plants (java moss, java fern, anubias) and hardscape (rocks, driftwood) is ideal, and will go a long way to giving this little fish a happy environment.

  • Common names: Otocinclus, Oto, Oto cat, Dwarf Sucker Fish
  • Scientific Name: Otocinclus Macrospilus
  • Life Span: 3-5 years
  • Size: 2 inches (5 centimeters)
  • Minimum tank size: 10 gallons
  • Care level: Beginner
  • Temperament: peaceful
  • Temperature: 72-82°F (22-28°C)
  • pH: 6.0-7.5

Diet: herbivore – high quality algae wafer or blanched veggies like broccoli and zucchini.

15. Dwarf Gourami (Trichogaster lalius)

Close up of dwarf gourami (Trichogaster lalius) swimming in aquarium

The dwarf gourami is a small freshwater fish part of the gourami family, growing up to 3.5 inches in length, it’s excellent for small tanks.

This stunning little fish is notable for its vibrant color variants: blue, flame, neon, honey. Their color combinations make them a stand out choice for many aquarist’s small nano tanks.

Unlike the larger aggressive gouramis species, the dwarf gourami is a peaceful community fish. They are commonly found swimming on the upper levels of a tank, so they fit well with mid and bottom dwelling fish.

  • Common names: Dwarf Gourami, Flame Gourami, Powder Blue Gourami, Red Gourami, Sunset Gourami
  • Scientific Name: Trichogaster lalius
  • Life Span: 4-5 years
  • Size: 2-3.5 inches (8.6 centimeters)
  • Minimum tank size: 10 gallons
  • Care level: Intermediate
  • Temperament: peaceful
  • Temperature: 72-82°F (22-28°C)
  • pH: 6.0-7.5
  • Diet: omnivore. Mix of animal protein and algae-based foods: high quality community flake food, spirulina, micro pellets.

Which Small Fish Is Right For Your Tank?

There really are some stunning nano fish available in the freshwater aquarium trade. Highlighting these gorgeous small fish shows that great things come in small packages.

When deciding on which fish is best for your small tank, it’s important to factor in the needs of the fish you want to keep. Your best bet is to tailor your tank around the species.

Remember that bigger tanks are actually easier to take care of in the long run. Plus, they give you more room for fish and plants.

It’s easy to see why nano tanks have become a craze. They’re beautiful but compact enough to fit lots of different budgets and living situations.

There are so many fun and creative things that can be done with these smaller tanks, the only limit is your imagination.

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Katherine Morgan
Hey, there! I'm Katherine from Northwest Florida. A nunchuck specialist, I've kept aquariums for over two decades, enjoy experimenting with low-tech planted setups and an avid South American cichlid enthusiast. If You'd like to see more of my tanks, check out my Instagram

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