How Many Zebra Danio in a 20-Gallon Tank?
In a 20-gallon tank you can comfortably keep about 6–14 Zebra Danio. As a schooling species, never keep fewer than 6.
Why
Stocking is driven by adult size and waste output, not just fish count. Zebra Danio reaches about 2" with a moderate bioload, and needs 64–77°F water at pH 6.5–8. Always cycle the tank and test water before adding livestock.
| Adult size | 2" |
|---|---|
| Minimum tank | 10 gallons |
| Temperature | 64–77°F |
| pH | 6.5–8 |
| Temperament | Semi-aggressive |
| Schooling | Yes — group of 6+ |
| Diet | Omnivore |
| Care level | Easy |
| Origin | South Asia (Ganges and Himalayan streams) |