How Many Discus in a 125-Gallon Tank?
In a 125-gallon tank you can comfortably keep about 5–12 Discus. As a schooling species, never keep fewer than 5.
Why
Stocking is driven by adult size and waste output, not just fish count. Discus reaches about 6" with a heavy bioload, and needs 82–88°F water at pH 6–7. Always cycle the tank and test water before adding livestock.
| Adult size | 6" |
|---|---|
| Minimum tank | 55 gallons |
| Temperature | 82–88°F |
| pH | 6–7 |
| Temperament | Peaceful |
| Schooling | Yes — group of 5+ |
| Diet | Omnivore |
| Care level | Advanced |
| Origin | Amazon basin |