JERUSALEM, Sept. 10 (Xinhua) -- Israeli researchers discovered a surprising social behavior among archerfish, the University of Haifa (UH) in northern Israel said in a statement on Sunday.
Such fish do not have the areas in the brain cortex that are considered responsible for social behavior and are also considered competitive and kleptoparasitic, without interdependence nor allomothering, that is, of offspring care by a group other than the parents.
However, a study published in the journal Communications Biology found these fish acting prosocially towards their tankmates.
Archerfish are renowned for their distinctive hunting method, by spitting water jets from their unique mouths to effectively snipe land-based insects and other small prey.
In the study experiments, archerfish always chose to spray water on a red spot, placed in an aquarium, which was worth a food reward to both itself and another archerfish beyond a transparent partition. The tested fish never targeted a black spot, which would reward only itself and not the other fish.
It was also found that without fish on the other side of the aquarium, the tested fish stopped choosing only the double-reward spot.
Furthermore, when the reward for the second fish was greater than for the tested fish, the latter felt "cheated" and unequal, and preferred to choose the reward that gave food only to itself.
"The findings show that even fish demonstrate complex social behaviors, which could indicate that sociality is an evolutionary tendency among different animal species," said UH researcher Orit Nafcha who headed the study.
"Apparently these social traits have survival importance in both cooperative and competitive societies, such as the fish we studied," she added. ■
