Fish have personalities too, and they could teach us a bit about ourselves

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We all can (probably) agree that dogs and cats have distinctive personalities, but it’d be hard to find someone making the same argument for fish. But a new study suggests (pdf) our little finned friends may have more complex personas than previously believed.

Researchers at the University of Exeter looked at how behavior in Trinidadian guppies, a common animal-research subject, differed based on their individual assessment of risk. Are some individual guppies more like piscine wing-suit pilots, while other prefer a more sedate lifestyle? The answer appears to be yes.

The scientists took a plastic predatory bird and made it appear to loom over each guppies’ individual tank. At different intervals, the plastic bird’s fake head was dropped into the water, simulating predation, and causing each fish to believe it was in danger. The researchers then observed the guppies’ behavior for a month, measuring how long after the stressor each guppy hid or otherwise showed reserved behavior. The results showed that some fish tended naturally towards cowardice, while others behaved in a way that we humans might call “brave.”

“When placed into an unfamiliar environment, we found guppies have various strategies for coping with this stressful situation,” says Thomas M. Houslay, an evolutionary ecologist at Exeter and lead researcher on the paper. “Many attempt to hide, others try to escape, some explore cautiously, and so on. The differences between them were consistent over time and in different situations.”

For a species whose individuals appear (to us humans) to be nearly identical, that was a small revelation for the researchers.

The next question they’d like to answer is whether, through DNA studies, they can determine if there’s a genetic basis to this kind of behavior. If so, the results could point to similar genes in other animals, including humans.