Guppies are beginner-friendly, low-maintenance fish that thrive in a 10-gallon tank, with a peaceful temperament and omnivorous diet. Males are smaller with vibrant colors, while females are larger ...

Striking colors that are seen only in the males of some species are partly explained by gene behavior, research into guppy fish suggests. Striking traits seen only in males of some species -- such as ...

Guppies can be fooled by optical illusions into believing objects are smaller or larger than they really are. This suggests they might not always make the best choices in their natural environment.

Some pet tropical fish are naturally placid, while others are fearsome predators.