Behaviour 2019
To the Left! Stimulus determines Behavioural Lateralization  of Population in Wild Zebrafish
Danita K. Daniel, Anuradha Bhat. Fish Ecology and Behaviour Lab, Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, , Mohanpur, West Bengal, India

Behavioural lateralization has been extensively studied across multiple taxa to decipher the mechanisms through which behaviour is controlled by either side of the brain.

Using wild-caught zebrafish in a detour test, we examined the effect of various kinds of stimuli such as predator, co-existing species, familiar and unfamiliar shoals of zebrafish and individuals of the same and opposite sex on behavioural lateralization. Although the population itself showed no inherent lateralization preference, each fish was found to be lateralized in either direction, the extent of lateralization being determined by individual properties such as sex and personality. However, the entire population displayed an inclination to turn to a specific side depending on the stimulus, even in the absence of conspecifics for social cues. 

This suggests that a certain side of the brain is controlling some specific response behaviours for most individuals of the population, highlighting the evolution of an adaptive measure useful in maintaining shoal cohesion which is vital for a social species such as the zebrafish.