Otocinclus: Oto Catfish Care Guide ...
Otocinclus: Oto Catfish Care Guide & Species Profile

Can you keep just two mollies?

No, you can’t keep just two mollies. Mollies are shoaling fish, which means they seek safety and comfort in numbers. Even though keeping a pair of mollies is better than keeping only a single molly, it’s not enough. Mollies are more comfortable when they live in a larger group of at least three or four fish.

Make sure the tank is big enough to accommodate them all. As a general rule, a one-inch fish requires one gallon of water. On average, mollies grow to be 3–4.5 inches long, so each fish needs around three gallons of space to swim freely.

Thus, a 10-gallon tank should suffice for three mollies to cohabit comfortably.