Brainy fish are found to be rarely out of their depth

Published on Tuesday 16 June 2009 22:45

STICKLEBACKS could be the "geniuses" of the fish world, scientists said yesterday after finding that the breed displays a sophisticated learning technique never before seen in animals.

Researchers tested the reactions of 270 nine-spined stickleback fish and found many of them could compare the behaviour of other sticklebacks with their own experience and choose which fish to copy to find more food.

The study authors say their findings suggest the fish might have a capability known as "hill-climbing" strategy which humans have but has not yet been found in other animals.

Co-author Professor Kevin Laland from the School of Biology at St Andrews University said: "Nine-spined sticklebacks may be the geniuses of the fish world. It's remarkable that a form of learning found to be optimal in humans is exactly what these fish do."

Researchers at St Andrews and Durham Universities put the fish in an aquarium and gave them worms from two feeders at either end of the tank. They initially preferred the feeder that was giving them more worms. Researchers then fed the fish more worms from the second feeder at the other end of the tank. The first group of fish were allowed to watch other fish feed before feeding themselves.

Around 75 per cent of fish were "clever" enough to know from watching the other fish that the feeder they had previously found to give them fewer worms was now giving out more and went for the second feeder.

But if the fish observed that feeders were giving roughly the same amount, they stuck with their own choice.

The scientists say the findings, published in the academic journal Behavioural Ecology, contribute to understanding of hu-man and animal brain evolution..