Fish food worth remembering

Nov 3 2014
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Trevor Hamilton’s research into fish memory sparks mini media feeding frenzy

Dr. Trevor Hamilton’s research into the brain power of African cichlids received a lot of attention this summer. BBC Nature News, The Telegraph, NBCNews.com, Huffington Post and Fox News quickly picked up on the release of the psychology prof’s new research at the Society for Experimental Biology conference in Manchester, U.K.

Why the international focus on fish brains? Popular knowledge had us believing that fish have a memory span of a mere seconds, but Trevor discovered that – at least when it comes to food and a type of fish called African cichlids – their memory is much longer term than we thought.

Measuring fish memory – cichlid training sessions

In a series of 20-minute training sessions over three days, Trevor and his student researcher, Erica Ingraham, trained individual fish to go to a certain zone in the aquarium by rewarding them with food. Then, after a 12-day rest period, they reintroduced the fish to the training area. Using motion-tracking software, the researchers recorded the cichlids’ swim paths and found the fish preferred areas where they had found food rewards before.

Trevor says this ability to connect locations with food could help fish survive in the wild, especially when food is scarce. "Fish that remember where food is located have an evolutionary advantage over those that do not," he says. "If they are able to remember that a certain area contains food without the threat of a predator, they will be able to go back to that area.”

The big picture for freshwater fish

While these findings are fascinating, they are only part of Trevor’s overall research program, which looks at learning, memory, and anxiety in fish and how the behaviours of these finned creatures can be altered by pharmacological substances and changes to their environment.

Trevor explains that knowing things like how long a fish can remember food is the first step in forming a baseline of the fishes’ capability. “In this case, we examined the ability of African cichlids to remember a food-based reinforcement task for 12 days. In the future, we will look at how environmental manipulation can alter this ability.”

Trevor’s current NSERC-funded research looks at how increased atmospheric carbon dioxide causes acidity in freshwater and how this may affect fish.

It’s still early, but Trevor says he can already see that higher carbon dioxide levels in the water these fish call home has pronounced effects on their behaviour. With help from his student researchers, he’ll be repeating pilot studies and looking closely at the statistics before coming to any conclusions.

Students present their high-level research in the U.K.

Students are a major aspect of this research program. “With busy semesters of teaching, I rely on my students to perform research, and they do so at a very high level,” Trevor says. “To date, all of my students have done very well and some have moved on to graduate studies in a variety of disciplines, including counselling psychology, neuroscience and urban planning.”

Students Erica Ingraham, Kayla Lucas, and Joshua Gallup accompanied Trevor to the Society for Experimental Biology conference where he presented his fish memory research and where they each presented their research to an international audience.

“Being able to present our research to such a large number of scientists from all over the world was something I will never forget,” says Erica, who will be continuing to research behavior in cichlids this year. “So was being interviewed by the BBC for an even wider audience. The interview itself was a little nerve-racking but well worth it in the end to see our efforts recognized.”

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More about Trevor’s own fish research and his students’ work: