Are guppies aggressive?

Guppies are generally peaceful, but males chase females constantly. Too many males and too few females can stress females and cause fin damage. The fix: keep at least two females per male, avoid fin-nippers. Overcrowding and wrong male:female ratios make things worse.

Our full guide covers male chasing, fin nipping, and all-male tanks. See also how to tell male from female guppies and guppy care.