One of the most important questions to ask when studying
social behavior concerns physiological processes that underlie
the species-specific behavioral variation. It is not surprising that
the integrative approach to behavior and physiology has received
considerable attention in fishes (Johnsson et al., 2006). Teleost fish
are able to exhibit unparalleled diversity when it comes to social
organization and behavioral output thus providing an excellent
opportunity to search for patterns of variation in physiological
proxies associated with social divergence. For instance, some species
live a solitary life while others tend to aggregate in schools and
develop the social skills that serve them well across their lifespan