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 ...

Scientists have long suspected that big brains come with an evolutionary price — but now they've published the first experimental evidence to support that suspicion, based on their efforts to breed ...

A long-term fish experiment reveals how a mechanism called density dependence, in which the population growth rate slows as the number of individuals rises, affects population dynamics on time scales ...

Duping a guppy is easier than duping a ring dove — at least when it comes to a classic optical illusion.