I have a 20-gallon tank. What can I keep?
A 20-gallon tank is a forgiving size to learn on: the water stays stable longer, and there’s room for a small school, a few bottom dwellers and a cleanup crew together.
A 20-gallon tank holds about 76 L. 11 of the 14 species we cover fit it so far; we add more every week.
Fits a 20-gallon tank, and how many
| Species | How many fit on their own | Adult size | Smallest tank |
|---|---|---|---|
| Betta fish | 1 | 2.5–2.8 in | 5 gallons (19 L) |
| Bronze corydoras | Up to about 6 (at least 5) | 2.8 in | 20 gallons (76 L) |
| Cherry shrimp | Up to about 40 (at least 6) | 1–1.5 in | 5 gallons (19 L) |
| Ember tetra | Up to about 16 (at least 6) | 0.9–1 in | 10 gallons (38 L) |
| Fancy goldfish | Up to about 1 | 6–8 in | 20 gallons (76 L) |
| Guppy | Up to about 12 (at least 3) | 1.5–2.5 in | 10 gallons (38 L) |
| Neon tetra | Up to about 16 (at least 6) | 1.4 in | 10 gallons (38 L) |
| Panda corydoras | Up to about 16 (at least 6) | 2.1 in | 10 gallons (38 L) |
| Platy | Up to about 4 (at least 3) | 2–2.6 in | 20 gallons (76 L) |
| Pygmy corydoras | Up to about 21 (at least 8) | 1 in | 10 gallons (38 L) |
| Zebra nerite snail | Up to about 5 | 1 in | 5 gallons (19 L) |
Counts are each species on its own, from our crowding model. Mixing species shares the space, so fewer of each fit: plan a mixed tank in the compatibility checker. Each species page says whether its count matches a published stocking list or is a cautious estimate.
Pairs that live well together in 20 gallons
Both species fit a 20-gallon tank on their own and every compatibility check passes at this size. This is about the two species getting along, not a stocking plan.
| Betta fish + Bronze corydoras | Can a betta live with bronze corydoras? Yes. |
| Betta fish + Ember tetra | Can a betta live with ember tetras? Yes. |
| Betta fish + Platy | Can a betta live with platies? Yes. |
| Betta fish + Pygmy corydoras | Can a betta live with pygmy corydoras? Yes. |
| Bronze corydoras + Ember tetra | Can a bronze corydoras live with ember tetras? Yes. |
| Bronze corydoras + Guppy | Can a bronze corydoras live with guppies? Yes. |
| Bronze corydoras + Neon tetra | Can a bronze corydoras live with neon tetras? Yes. |
| Bronze corydoras + Zebra nerite snail | Can a bronze corydoras live with nerite snails? Yes. |
| Bronze corydoras + Panda corydoras | Can a bronze corydoras live with panda corydoras? Yes. |
| Bronze corydoras + Platy | Can a bronze corydoras live with platies? Yes. |
| Bronze corydoras + Pygmy corydoras | Can a bronze corydoras live with pygmy corydoras? Yes. |
| Cherry shrimp + Ember tetra | Can a cherry shrimp live with ember tetras? Yes. |
| Cherry shrimp + Pygmy corydoras | Can a cherry shrimp live with pygmy corydoras? Yes. |
| Ember tetra + Neon tetra | Can an ember tetra live with neon tetras? Yes. |
| Ember tetra + Panda corydoras | Can an ember tetra live with panda corydoras? Yes. |
| Ember tetra + Pygmy corydoras | Can an ember tetra live with pygmy corydoras? Yes. |
| Fancy goldfish + Zebra nerite snail | Can a fancy goldfish live with nerite snails? Yes. |
| Guppy + Zebra nerite snail | Can a guppy live with nerite snails? Yes. |
| Guppy + Panda corydoras | Can a guppy live with panda corydoras? Yes. |
| Guppy + Platy | Can a guppy live with platies? Yes. |
| Neon tetra + Panda corydoras | Can a neon tetra live with panda corydoras? Yes. |
| Neon tetra + Pygmy corydoras | Can a neon tetra live with pygmy corydoras? Yes. |
| Zebra nerite snail + Platy | Can a nerite snail live with platies? Yes. |
| Panda corydoras + Pygmy corydoras | Can a panda corydoras live with pygmy corydoras? Yes. |
Too big for 20 gallons
- Angelfish: angelfish need at least 30 gallons.
- Common goldfish: common goldfish need at least 75 gallons.
- Tiger barb: tiger barbs need at least 30 gallons.
Before you buy fish
Cycle the tank first and check it’s ready, then use the compatibility checker to test your plan.