Fish Can Count - Latest Research On School Sizes

Link below to an episode of the BBCs ‘The Infinite Monkey Cage’ in which they give the most up to date position on research into the ability of fish to count.  Go to 18:40 for a listen.

https://www.bbc.co.uk/sounds/play/m00024ph

From this and a little of my own research it seems fish dont necessarily count “one, two, three” they do count using ratios - we humans do this too subconsciously. Such a counting method gives the ability to differentiate between group sizes e.g. a group of size 3 vs 4 and a group of size 4 vs 5 - as the ratio numbers get larger the ability to distinguish between a group of one larger becomes more tricky. Fish have been found to be able to  distinguish between group sizes of 7 and 8 - of course there is the fish doing the counting to take into consideration too. Meaning this gives a maximum of 9.

This ability gives the fish the whereabouts to find a school of sufficient size for safety purposes. Previously it has been advised that schools of 6 are appropriate for schooling fish to make them appear comfortable - most places also say the more the better of course and this fits with others experiences. But this latest research seems to suggest that the magic number may in fact be 9 rather than 6. They seem to do the research on the same kind of fish we would stock input aquariums too which is useful.

So if you are considering your stocking and/or school sizes you might want to take this into consideration - I know I will be in my future stocking planning.

Oops yes indeed - added to my original post @fcmf

It also possibly explains why smaller fish seem to do better with larger shoals - when you are tiny, the more of you there are the safer you feel.