Fish also know logical thinking

Male fish, like humans, use a complex logical thinking to assess opponents. A tiny African fish called cichlid tracks how other males fight for territory to decide which one to defeat to maintain their status.

Children also have this kind of thinking, called comparative comparison, as well as other primates and mice. This is the first time scientists at Stanford University, USA, have demonstrated this behavior in fish.

This outstanding 'fish' ( Astatotilapia burtoni ) shows a black stripe on the face, a sign that it is very good at fighting. (Photo: ABC Online)

"This result shows that fish also use comparative associations to find their place in the social ladder," said Russell Fernald, a professor of biology. "I was surprised to see that they could do so only by watching other males fight."

Male cichlids climb up the social ladder by fighting and defeating their opponents. The fish that often fail will slip long in position.

Fernald and his team have demonstrated the logical thinking of fish by arranging for 8 fish to follow other types of fighting in an aquarium. They used Astatotilapia burtoni fish with black stripes on their faces.

If a defeated fish is easily recognized by the black stripe on the face, it disappears temporarily when it loses away from the winning opponent.

When every battle is over and the fish recover from the war, the researchers look at how the observed fish picks their opponents. The results show that most observers choose the weakest fish.

"Our experiments show that male cichlids can quantify their ability to succeed only by observing. From an evolutionary perspective, collusion will help them save time and energy. Fernald said.

MT