How Many Pearl Danio in a 40-Gallon Tank?
In a 40-gallon tank you can comfortably keep about 6–22 Pearl Danio. As a schooling species, never keep fewer than 6.
Why
Stocking is driven by adult size and waste output, not just fish count. Pearl Danio reaches about 2.5" with a moderate bioload, and needs 68–78°F water at pH 6.5–7.5. Always cycle the tank and test water before adding livestock.
| Adult size | 2.5" |
|---|---|
| Minimum tank | 20 gallons |
| Temperature | 68–78°F |
| pH | 6.5–7.5 |
| Temperament | Semi-aggressive |
| Schooling | Yes — group of 6+ |
| Diet | Omnivore |
| Care level | Easy |
| Origin | Southeast Asia |