Fish start copying each other as group size increases

Scientists from Australia are researching the movements of schools of mosquitofish to investigate if the members of larger groups conform more than the ones in a smaller setting.

The researchers have been scrutinising the movements of schools of mosquitofish that are able to tolerate extreme salinity and temperature.

The fish known Gambusia holbrooki was introduced into Australia in 1925 and live in areas where survival of other fish is difficult.

Sydney University biological scientist Ashley Ward said that they examined the behaviour of individual fish and found that each moves in a different, predictable and consistent way – even though all were approximately the same size, age and health.

The fish were retained their individuality when in small groups but assumed a sort of collective identity as the size of the group increased.

Ward said that the larger a group, the more these fishes copied each other and became components rather than individuals, the Age reported.

He explained that to be effective, these fishes have to be collective.

To measure the behaviour of the individual fish automated tracking software was used.

Each fish was measured twice: once when they were in a group and once when they were on their own.

Ward said that the order in which this was done was randomised, then the researchers studied how an individual’s movements – including speed, turning rate, and so on – were affected by being in a group.

The scientists found that individuality varied with group size.

Ward said that as the size of a group increased, the more they conformed. (ANI)