How Many Molly in a 55-Gallon Tank?
In a 55-gallon tank you can comfortably keep about 3–9 Molly. As a schooling species, never keep fewer than 3.
Why
Stocking is driven by adult size and waste output, not just fish count. Molly reaches about 4.5" with a heavy bioload, and needs 72–82°F water at pH 7.5–8.5. Always cycle the tank and test water before adding livestock.
| Adult size | 4.5" |
|---|---|
| Minimum tank | 20 gallons |
| Temperature | 72–82°F |
| pH | 7.5–8.5 |
| Temperament | Peaceful |
| Schooling | Yes — group of 3+ |
| Diet | Omnivore |
| Care level | Easy |
| Origin | Southern US to Colombia |