Stupid as a Fish?

Compared to mammals, fish are often underestimated and dismissed as less complex organisms. To refute this hasty conclusion, Horst Bleckmann presents to you the highly developed cognitive abilities of fish.

Did you know, for example, that fish are the largest group of all vertebrates, with about 30,000 species, and that they colonize all aquatic habitats? For this immense feat, they have...