The impressive advances in scientific knowledge about fish cognition were documented in a recent study by the biologists Culum Brown, Keven Laland, and Jens Krause for the journal Fish and Fisheries: "Although it may seem extraordinary to those comfortably used to pre-judging animal intelligence on the basis of brain volume, in some cognitive domains, fishes can even be favorably compared to non-human primates," the scientists observed.
To reinforce this conclusion, Brown, Laland, and Krause cited more than 500 new studies of fish that show the animals’ advanced capacities for reasoning, memory, and social interaction. Fish are now known to be capable of using tools, recognizing and distinguishing between other fish in their shoals based on social hierarchy, and exhibiting impressive feats of memory and problem solving, such as recalling a specific escape route from a net up to 11 months after having learned it.