Consistency among different tasks of left-right asymmetries in lines of fish originally selected for opposite direction of lateralization in a detour task.

Lines of fish, Girardinus falcatus preferentially turning rightward (RD) or leftward (LD) when facing a dummy predator visible behind a barrier have been obtained through selective breeding. To check whether lateralization was maintained in other behavioral responses, five different tests were carried out. They comprised measures of (1) turning direction in a T-maze; (2) proportion of clockwise and anticlockwise direction of rotation in a circular arena; (3) preferential eye use by females during shoaling behavior (i.e. while looking at their own mirror image reflection); (4) preferential eye use by males during sexual behavior (i.e. while turning around a barrier to join a group of females); and (5) preferential eye use by males during agonistic behavior (i.e. while attacking a rival visible in a mirror). In all five tests the two selected lines showed opposite direction of lateralization. Results thus indicate that behavioral asymmetries in the detour test are predictive of lateralization in other types of behavioral tests. Moreover, results show that RD and LD fish have a similar but left-right reversed pattern of subdivision of cognitive/ behavioral functions, which is suggestive of a similarly left-right reversed (mirror image) brain organization.