Social relationship as inducer of immunological and stress responses in matrinxã (Brycon amazonicus).

Matrinxã (Brycon amazonicus) is a freshwater neotropical fish species with a social interaction and aggressive behavior, especially in crowded environments. This species' social structure is established by agonistic interactions, which increase significantly at the fifth hour, when compared to the first and second hours of confinement, when each dominant fish competes with other individual for a conditioned territorialism. This social relationship also induces a complex physiological response in the organism, which generates an acute stimulation from the stressor agent.