Seasonal changes in territoriality and frequency of agonistic behavior in two densities of juvenile brown bullhead,Ictalurus nebulosus

Synopsis Incidence of territoriality and frequency of six agonistic action patterns of juvenile brown bullhead, Ictalurus nebulosus, were observed in the laboratory over a two year period at two fish densities under conditions of constant light and temperature. High density fish showed little territoriality or agonistic behavior while low density fish displayed an annual cycle of agonistic behavior and territoriality. Agonistic behavior frequency and incidence of territoriality peaked in February and March and were higher the second year when compared with the first.