When it comes to choosing their friends, fish are most likely to bond over favorite foods. According to a recent study published in the journal Behavioral Ecology and Sociobiology, some types of fish bond when they eat the same thing for dinner, choosing to shoal with other fish who consume the same foods they do—regardless of species.
Scientists at the School of Life Sciences at the University of Lincolnshire studied the shoaling behavior of three-spined sticklebacks and nine-spined sticklebacks. They found that when they fed the fish different types of food, those fish who consumed the same foods tended to associate with each other, whether or not they were the same species. When they fed the sticklebacks the same food, meanwhile, the fish had no particular preference for their own species.
via Mental Floss
