Demo
Save the Little Fish demo · Small, about 20 gal · gentle current, like a stream · running 409 days · shared October 2026
Everything the shop had, in one 20-gallon. Every fish here is fine on its own; together they don't work.
Puntigrus tetrazona
Sumatra and Borneo · stream
Fin nipper. Keep it away from long-finned fish.
Photo: Ingvar-fed, CC BY-SA 3.0
× 6
Constantly chasing the betta.
Betta splendens
Rice paddies and marshes of Thailand · swamp or paddy
Lone male. Males fight. Keep one, or give each his own space.
Long fins. Fin nippers will pick on it.
Photo: ErgoSum88, Public domain
× 1
Fins torn within a week.
Pterophyllum scalare
Flooded forests of the Amazon basin · flooded forest
Predator. Eats any fish that fits in its mouth.
Long fins. Fin nippers will pick on it.
Photo: Rjcastillo, CC BY 4.0
× 1
Paracheirodon innesi
Upper Amazon basin: Peru, Colombia, Brazil · blackwater stream
Photo: Holger Krisp, CC BY 3.0
× 8
Every species is comfortable in this range.
No two species here can cross, so any fry that turn up are pure.
Angelfish feel safe in groups of 5 or more; you have 1. Small groups hide, lose colour and get picked on.
Fin-nippers go for long, slow fins. Torn fins get infected. Don't keep them together.
An adult angelfish reaches 15 cm and eats any fish that fits in its mouth, even ones it grew up with.
Too much waste for the water. Remove fish, pick a bigger tank, or plan on heavy filtration and large water changes.
A few bottom fish, such as corydoras, use the floor and eat food that sinks past the others.
Size and stocking checks use a typical tank of the size you picked. Add the real length and volume for a sharper answer.
Care data for Angelfish, Betta (Siamese fighting fish), Neon tetra, Tiger barb is estimated or taken from the genus, not yet checked against a source.
