Strategy to help rainbow fish evade enemy attacks

New research shows that rainbow fish defend themselves by luring predators to attack the head and then suddenly changing direction to escape.

Rainbow fish or guppies (Poecilia reticulata) are native to South America. With an average length of only 2.5 cm, they have many predators in the wild, the most common being the tilapia spearheaded (Crenicichla). In order to survive, this tiny freshwater fish has developed a very unique defense skill.

Picture 1 of Strategy to help rainbow fish evade enemy attacks
A pair of rainbow fish (male above). (Photo: NUS).

In a recent study conducted by the University of Exeter in UK, biologists found that rainbow fish have the ability to change the iris color to look more striking, in order to lure the enemy to attack towards the head instead. because of other parts of the body.

They actively wait for predators to rush forward, then use quick reflexes to whip their head to the side and swim away. The entire process takes only 3% seconds, so fast that it cannot be seen by the naked eye.


Slow-motion footage from the high-speed camera shows the rainbow fish avoiding the spear tilapia attack. (Video: Exeter University).

"The eye is one of the most recognizable structures in the natural world. Many species have undergone a long evolutionary process to develop eye disguise, in order to avoid the attention of predators. However, Rainbow fish do the opposite , " said Dr. Robert Heathcote from the University of Exeter.

This self-defense tactic was very effective when it helped to increase the rainbow fish's successful escape rate by more than 38% compared to those that did not change their eye color, according to the team's observations. Another incredible finding is that the larger the rainbow fish, the higher the chances of successful escape.

Picture 2 of Strategy to help rainbow fish evade enemy attacks
Simulate the defensive tactics of the rainbow fish. (Photo: Exciter University).

"Normally, bigger animals become slower and more vulnerable to attack. However, by changing the iris color, rainbow fish actually reverses this phenomenon. Larger fish with black eyes more will have a lower rate of being eaten , " Heathcote explained.

Details of the study have been published in Current Biology.

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