Staying clean keeps seafish smart

International researchers led by an Université de Montréal biologist has found that infection with parasites makes it harder for seafish living in coral reefs to think.

The study, conducted at the Lizard Island Research Station in Australia by assistant professor Sandra Binning and her team, was published in Proceedings of the Royal Society B: Biological Sciences.

Sandra Binning checks on one of her fish and gives it a tasty meal of fish flakes for breakfast. Credit: Dominique Roche

It highlights the important role of both parasites and cleaning organisms in the decision-making abilities of reef fish.

Binning and her team found that sick seafish can get well again by seeking out other animals like the blue-streaked “cleaner wrasse,” a common aquarium fish that eats harmful parasites off their “clients,” helping keep them healthy.

“We collected wild damselfish with or without access to cleaner wrasse and tested their ability to solve a feeding test in the lab.” Binning recalled. “We then compared their performance to fish that we infected with parasites experimentally.”

“We found that infection with parasites, especially in high numbers, really affects the ability of fish to learn.”

These results may not be surprising to anyone who’s been sick and tried to do activities requiring thinking and concentration. “When we’re sick, our body diverts resources away from our brain towards fighting off the infection,” Binning noted. “This makes it harder for us to think and learn.”

Humans may also benefit from staying parasite-free. “Studies have found that schoolchildren with stomach worms perform worse on standardized tests that their parasite-free peers,” said Binning. “Treating these kids with anti-parasite medication improves their performance.”