Demo
Save the Little Fish demo · Large, 55–75 gal · calm, like a pond or swamp · running 1505 days · shared October 2026
Tannin-stained water, leaf litter and roots. Soft, acidic and warm enough for rams, cool enough for the tetras.
Paracheirodon axelrodi
Rio Negro and upper Orinoco, Brazil and Venezuela · blackwater stream
Photo: Paolo Neo, Public domain
× 15
They school tightest when the lights first come on.
Carnegiella strigata
Amazon basin, Peru and Brazil · blackwater stream
Jumper. Keep a tight lid on the tank.
Photo: SOK, CC BY-SA 4.0
× 6
Keep the lid on: two jumped before we sealed the gaps.
Tetras · NannostomusStaple
Nannostomus beckfordi
Amazon basin and the Guianas · blackwater stream
× 6
Corydoras sterbai
Rio Guaporé, Brazil and Bolivia · river
Photo: Matthew Mannell, Public domain
× 8
Always busy in the sand.
Mikrogeophagus ramirezi
Llanos savanna streams, Orinoco basin · stream
Photo: Eric Mengel, Public domain
× 2
The pair guards a patch of leaf litter but leaves everyone else alone.
Every species is comfortable in this range.
No two species here can cross, so any fry that turn up are pure.
Some of these fish jump, especially when startled.
A rough estimate based on adult body size and tank volume.
Something at the top, in mid-water and on the bottom, so the whole tank looks alive.
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 Cardinal tetra, German blue ram, Golden pencilfish, Marbled hatchetfish, Sterba's corydoras is estimated or taken from the genus, not yet checked against a source.
