Are fish stupid?

Contrary to the popular assumption that fish are stupid, scientists have discovered that they are actually adept learners, with distinct personalities that change as they pick up information about the world.

The study found that rainbow trout (Oncorhynchus mykiss) remember experiences so well that they alter their behavior in line with what they learn, and that they have contrasting personalities. Some are bold and some are shy. The bold fish take risks, they are quick to learn, more aggressive and active. Shy fish are cautious and timid, and spend more time under cover.