Memories of Fish

Illustrations and words – Nick Sidle

Don’t tell fish they only have short memories, they may hold it against you for a very long time

Digital illustration – Black Sea Bream, Spondyliosoma cantharus

It has long been said that fish, Goldfish in particular, only have memories measured in seconds, possibly as short as three seconds. There have long been grounds to question this. Some fish form stable pair bonds and the ‘who are you?’ moment after three seconds apart on the reef could be awkward. Research has confirmed far more developed memory functions than a few seconds including in Goldfish, the three second hypothesis has for some time been confirmed as wrong. A recent study raises the need for respect of fish cognitive functions even further. The Max Planck Institute of Animal Behaviour in Southern Germany looking at Sea Bream in the Mediterranean has shown that the fish have a real ability to analyse the dress sense of divers and translate that information into advantageous behaviour:

Max Planck Institute – Wild fish can recognize individual divers

Biology Letters, The Royal Society – Wild fish use visual cues to recognize individual divers

What the study showed was an ability to learn to recognise divers by the colours of their equipment and know from a developed response which one to follow for food. Two divers were in the water and only one went on to feed the fish. If they wore different coloured sets of equipment, for example the fins, then the fish learned which diver to follow. If they wore identical equipment, the fish were unable to choose which to go with. As one of the researchers notes on The Institute web site, ‘Now we know they see us, it’s time for us to see them.’