Nano fish
Being small is not the same as suiting a small tank. Some 3 cm species shoal hard enough to need most of a metre to swim in — small, but not nano. This list holds only the ones where both are true: they stay small, and a small tank genuinely suits them.
Why these
Adult length up to 4 cm, and a minimum volume of 40 litres or less.
15 species
White Cloud Mountain Minnow
Tanichthys albonubes
4 cm · 5–24 °C · ≥ 40 l
Celestial Pearl Danio
Danio margaritatus
2.5 cm · 20–26 °C · ≥ 40 l
Ember Tetra
Hyphessobrycon amandae
2 cm · 22–28 °C · ≥ 40 l
Least Killifish
Heterandria formosa
3.5 cm · 15–26 °C · ≥ 20 l
Medaka Ricefish
Oryzias latipes
4 cm · 8–28 °C · ≥ 40 l
Pygmy Corydoras
Corydoras pygmaeus
3 cm · 22–26 °C · ≥ 40 l
Salt and Pepper Cory
Corydoras habrosus
3.5 cm · 20–26 °C · ≥ 40 l
Chili Rasbora
Boraras brigittae
2 cm · 24–28 °C · ≥ 30 l
Clown Killifish
Epiplatys annulatus
3.5 cm · 20–26 °C · ≥ 20 l
Dwarf Rasbora
Boraras maculatus
2.5 cm · 22–28 °C · ≥ 30 l
Green Neon Tetra
Paracheirodon simulans
2.5 cm · 23–30 °C · ≥ 40 l
Scarlet Badis
Dario dario
2.5 cm · 18–26 °C · ≥ 30 l
Sparkling Gourami
Trichopsis pumila
4 cm · 22–28 °C · ≥ 30 l
Strawberry Rasbora
Boraras naevus
2 cm · 20–28 °C · ≥ 40 l
Bumblebee Goby
Brachygobius doriae
4 cm · 22–29 °C · ≥ 40 l
Which of these go together?
A list tells you what is possible on its own. Whether three of them share a tank without one eating another — and whether your volume, temperature and hardness actually allow it — is what the planner works out.
Open the planner