Monday, September 21, 2015

Do fish really have a three second memory?

Archer fish
This Archer fish eyed me up and spat at me. They catch their prey (usually insects) by shooting them with water so they fall into the water where they can be eaten.
The fact that the myth that fish have a “three-second memory” persists says much more about human gullibility than it does about fish cognition. I’ve heard someone say this whilst simultaneously approaching a tank to feed fish – who are gathering at the surface of the water in anticipation of feeding. Who in this equation has the three-second memory?

The concept that fish forget is a powerful and convenient one – some use it to argue that if they only have a three second memory, it doesn’t really matter how we keep or treat fish.

But there is plenty of evidence that fish think, feel and even remember – for years.

Associate Professor Culum Brown is an expert on fish cognition and behavioural ecology. He addressed the Human Animal ResearchNetwork earlier this year and shared some insights. One thing I learned is that (some) very lucky fish researchers are required to do fieldwork that involves snorkelling around Lizard Island.

But I learned some other things too.
  • Fish absolutely feel pain. Their pain receptors are similar to those in vertebrates; their behaviour changes in response to a painful stimulus and normalises when pain relief is given; and they anticipate and avoid sources of pain. Some fish develop “hook shyness” after one horrific encounter, and this can persist for years.
  • Fish feel pleasure. Coral reef fish like having their backs rubbed, for example – and its not just because they look like they’re enjoying it. Scientists have measured stress hormones like cortisol before and after these sessions and found that yep, a back rub reduces stress in fish.
  • Fish demonstrate hallmarks of intelligence including learning and memory, long-term memory, spatial awareness, social intelligence (fish will behave differently depending on who is watching them – just like us), nest building and even tool use.

If you want to learn a bit more about fish, including some of the studies on which the above conclusions are based, check out Dr Brown’s talk here.