How Many Threadfin Rainbowfish in a 40-Gallon Tank?
In a 40-gallon tank you can comfortably keep about 8–62 Threadfin Rainbowfish. As a schooling species, never keep fewer than 8.
Why
Stocking is driven by adult size and waste output, not just fish count. Threadfin Rainbowfish reaches about 1.6" with a light bioload, and needs 72–86°F water at pH 5.5–7.5. Always cycle the tank and test water before adding livestock.
| Adult size | 1.6" |
|---|---|
| Minimum tank | 15 gallons |
| Temperature | 72–86°F |
| pH | 5.5–7.5 |
| Temperament | Peaceful |
| Schooling | Yes — group of 8+ |
| Diet | Omnivore |
| Care level | Moderate |
| Origin | Northern Australia and New Guinea |
More fish for a 40-gallon tank → Threadfin Rainbowfish tankmates →