EN
Labroides dimidiatus (Labridae) is a model fish in research concerning cleaner fish mutualism. Recent studies shows that cleaners are capable to build up complicated relationships (Bshary and Würth 2001). Cleaners recognize clients individually, they remember past interactions with clients, they may cooperate, reconcile, manipulate, cheat, produce signals out of context, and use predatory clients as social tools against aggressive clients (Bshary 2011). The apparent complexity of cleaner fish behavior makes them a particularly interesting object of comparative analysis of morphology and cytoarchitecture of brain and brain centers in telencephalon, optic tectum and cerebellum, parts of the brain potentially involved in cognitive functions related to behaviors in complex social environment (Demski and Beaver 2001). A cytoarchitectonic study shows in the telencephalic regions responsible for the control of the processes related to visual information, a complex cortical structure; a columnar arrangement of cells in the region responsible for the integration of multimodal information; and duplication of nuclei in vetral part of the telencephalon. Nuclei connected with olfactory information were poorly developed. Proportions, complexity and size of the optic tectum layers, tori semicircularis, tori longitudinalis, and the cerebellum proved diversified importance of visual organs, small role of hearing and lateral line, and complex and well developed skills associated with the spatial mapping and complex locomotion.