Researchers have found that a species of tropical fish can infer social relations between individuals, a discovery that may reverse the common view that fish do not have high cognition abilities.
In their latest study, a team led by Osaka City University professor Masanori Kohda conducted experiments to see whether Julidochromis transcriptus, a cichlid species indigenous to Lake Tanganyika in Africa, has transitive inference ability.
The cichlid is known to form highly organized social systems in which breeding is carried out cooperatively. Previous studies also found that the fish recognizes strong and weak relationships, based on experience in direct interactions.
Hypothesizing that the fish, also called the Masked Julie, has transitive inference ability, the Osaka City University-led team had similarly sized pairs of males fight each other under observation by other cichlids. Later, the researchers let the winners, called A, and the observers, or C, fight each other while being monitored by the losers to A, labeled B. Finally, the C cichlids that prevailed were shown to B members through an opaque shield.
As a result, most of the B fish refrained from acting aggressively toward the C winners, confirming that fish B correctly inferred that it was subordinate to fish C after watching fish C defeating fish A, the researchers said in an article published online by the Swiss journal Frontiers in Ecology and Evolution.
The results proved the fish has high information-processing abilities, Kohda said. I want to conduct similar experiments on other species.
The Japan Times Ltd.