These Tiny Fish ‘Have Different Personalities’ – May Be Better Than Us

Scientists are astonished by the unexpected behavior of Trinidadian guppies, tiny fish that have defied the conventional wisdom of the “volunteer’s dilemma.” Typically, the dilemma suggests that individuals are less likely to cooperate when they are part of a large group. However, contrary to this notion, guppies have displayed a remarkable willingness to cooperate.

A recent study conducted by the University of Exeter shed light on this phenomenon. The researchers observed that guppies in larger groups were more inclined to take risks by approaching a predator in order to gather information for the collective.

Rebecca Padget, from Exeter’s Centre for Research in Animal Behaviour, explained the delicate balancing act faced by guppies when encountering a potential threat.

“When faced with a possible predator, guppies have to balance risks,” she said.

“At least one guppy needs to approach, to find out if there is a threat. An individual that does this could get eaten. However, if none of the guppies take this risk, the whole group is in danger. In this ‘volunteer’s dilemma’, mathematical models suggest that individuals in larger groups should be less willing to cooperate. In a larger group, there’s more chance another guppy will take the risk.”

To investigate this further, the researchers placed a clay model of a pike cichlid, a natural predator of guppies, in a tank with small (5), medium (10), and large (20) groups of guppies. Surprisingly, it was the guppies in the large groups who displayed the highest propensity to approach and inspect the predator. On average, individuals in large groups inspected the predator 14 times during the seven-minute trials, while those in medium groups exhibited the least inclination, inspecting it only seven times each. Guppies in medium groups also sought refuge behind plants or near the tank’s gravel edge for extended periods.

Padget emphasized that the exact reasons for guppies in larger groups cooperating more frequently remain uncertain. She speculated that the presence of more cooperative individuals within larger groups might influence the behavior of others, as guppies are known to exhibit different personalities.

After inspecting the predator, guppies returned to their group.

Previous research has demonstrated that their behavior upon returning serves as a danger signal to the rest of the shoal.

An “inspection” was recorded when a guppy approached within 30cm of the predator, typically performed by individuals or small sub-groups within the main shoal.

The findings of this study were published in the journal Proceedings of the Royal Society B.

Source: 10.1098/rspb.2023.0790 

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