Best Fish for Small Tanks (Under ~10 Gallons)

Species genuinely happy in a compact 20–40 litre setup.

By The Aquarium DB Team • 59 species
Ember Tetra Ember Tetra Neon Green Rasbora Neon Green Rasbora Ramshorn Snail Ramshorn Snail Red Lip Nerite Snail Red Lip Nerite Snail Nerite Snail Nerite Snail Assassin Snail Assassin Snail Cherry Shrimp Cherry Shrimp Endler's Livebearer Endler's Livebearer Glowlight Danio Glowlight Danio Gold Ring Danio Gold Ring Danio Malaysian Trumpet Snail Malaysian Trumpet Snail Neon Tetra Neon Tetra Tail-spot Corydoras Tail-spot Corydoras Trinidad Guppy Trinidad Guppy Glowlight Rasbora Glowlight Rasbora Flame Tetra Flame Tetra Ghost Shrimp Ghost Shrimp Golden Dwarf Barb Golden Dwarf Barb Amano Shrimp Amano Shrimp Japanese Trapdoor Snail Japanese Trapdoor Snail Mystery Snail Mystery Snail Bloodfin Tetra Bloodfin Tetra Desert Goby Desert Goby Guppy Guppy Betta Betta Croaking Gourami Croaking Gourami Roundtail Paradise Fish Roundtail Paradise Fish Celestial Pearl Danio Celestial Pearl Danio Chili Rasbora Chili Rasbora Emerald Dwarf Danio Emerald Dwarf Danio Exclamation Point Rasbora Exclamation Point Rasbora Ruby Tetra Ruby Tetra Scarlet Badis Scarlet Badis Strawberry Rasbora Strawberry Rasbora Dwarf Spotted Rasbora Dwarf Spotted Rasbora Neon Blue Rasbora Pea Puffer Pea Puffer Clown Killifish Clown Killifish Tailspotted Oto Tailspotted Oto Rainbow Emperor Tetra African Dwarf Frog African Dwarf Frog Jelly Bean Tetra Jelly Bean Tetra Strawberry Betta Strawberry Betta Wine Red Betta Wine Red Betta Blue Turbo Snail Blue Turbo Snail Badis Badis Hummingbird Tetra Crystal Red Shrimp Crystal Red Shrimp Crimson Red Betta Tiger Otocinclus Tiger Otocinclus Spotfin Betta Spotfin Betta Eastern Betta Fire Red Licorice Gourami Fire Red Licorice Gourami Sparkling Gourami Sparkling Gourami Peaceful Betta Peaceful Betta Smaragd Betta Mahachai Betta Mahachai Betta Tucano Tetra Tiger Shrimp Tiger Shrimp
Buyer's guide

How to choose a small-tank fish

Small tanks suit small, low-waste species — nano fish, shrimp, snails and a couple of specialists like the betta and the pea puffer. The hard rule is to stay well within each species’ minimum tank size and resist the urge to add "just one more".

A smaller water volume swings temperature and chemistry faster, so plant heavily for stability and cover, keep stocking light, and stay disciplined with water changes. Done right, a nano tank is one of the most rewarding ways to keep fish.

FAQ

Frequently asked questions

What fish can live in a 5-gallon (19 L) tank?

Realistically a single betta, a colony of cherry shrimp, or a small group of the tiniest nano fish — and not much else. Filtration and a heater are still essential.

Is a bigger tank easier than a small one?

Usually, yes. A larger water volume is more stable and forgiving, so beginners often find a 20-gallon community easier to keep than a tightly stocked nano tank.