“Experience dependent learning of Handedness” in Scale-eating Fish


A research group led by Yuichi Takeuchi, Department of Anatomy and Neuroscience, Faculty of Medicine, University of Toyama, has demonstrated that behavioral laterality of the cichlid fish is determined by the experience during early developmental stages, immediately after they start scale-eating.

Background and overview

Toyama, Japan – The preference for using one side of the body over the other, as observed typically in human handedness, is referred to as behavioral laterality. Increasing numbers of studies are revealing that, aside from humans, other vertebrates, and even invertebrates, exhibit at least some degree of handedness.

Behavioral laterality is advantageous to foraging, defending against competitors, being vigilant against predators, or attending to prospective mates. It has been thought that when this is acquired depends on heredity and postnatal learning, but the specific time was surrounded by many mysteries due to the difficulty of long-term observation.

Research group of Yuichi Takeuchi of the University of Toyama have now revealed how and when behavioral laterality arises. They did this by using the scale-eating predator cichlid Perissodus microlepis (P. microlepis), found in Lake Tanganyika in Africa, at its developing stage. They recently published their findings in Scientific Reports.

“P. microlepis is an attractive model of behavioral laterality because the adult fish exhibits clear asymmetric mouth morphology and conspicuously lateralized predatory behaviour; left- or right-sided attack of the prey fish,” study corresponding author Takeuchi says.

The researchers successfully bred P. microlepis in our laboratory. The juvenile and young fish retain the ability to learn different aspects of laterality in foraging behavior, whereas adults do not. Juvenile at just starting scale-eating strengthened not only attack side preference but also developed body flexion movement during the dominant side attack through scale-eating experience during the short periods of scale-eating experience (amounting to a total of up to 5 h in the laboratory). The findings suggest that P. microlepis develop lateralized scale-eating behavior with phase-dependent learning.

Interestingly, young fish did not develop the lateralized body flexion movement. Thus, the lateral difference in behavioral kinetics is naturally determined. Based on our findings, we suggest that P. microlepis develop lateralized scale-eating behavior with phase-dependent learning.

“Our findings provide the acquisition of behavioral laterality is quite similar to that of vocal communication in songbird and human that can be limited to learn at specific early stage of development (so-called “sensitive phase”),” coauthor Oda says. “Given the abundance of available tools for investigating changes at the neurological and genetic levels in fish, the scale-eater can pave the way to improve our understanding of the brain systems underlying phase-specific learning in predator-prey interactions.”

Original article information


Experience-dependent learning of behavioral laterality in the scale-eating cichlid Perissodus microlepis occurs during the early developmental stage


Yuichi Takeuchi, Yuna Higuchi, Koki Ikeya, Masataka Tagami and Yoichi Oda