Habitat structure directly affects aggression in convict cich- lids Archocentrus nigrofasciatus

Abstract Aggressive behavior can be an important factor in determining how animals use and divide space and resources. Pre-vious studies have shown that aggression in fishes can be influenced by a variety of factors, including water temperature and re-source levels. In this study, we tested if the amount of habitat structure in the environment affected aggression levels in female convict cichlids Archocentrus nigrofasciatus. We performed a laboratory experiment in which we placed female convict cichlids into an aquarium with low or high amounts of habitat structure and monitored the dominant female's behavior toward the subor-dinate female. Aggressive behavior in convict cichlids primarily consists of chases and bites. We found that the total time the dominant female spent chasing the subordinate female was greater when there was a low amount of habitat structure as compared to when there was a high amount of habitat structure. We also found that both the average duration of a chasing bout and the number of bites directed at the subordinate fish increased when there was a low amount of structure, but the number of chases did not. These results indicate that increased habitat structural complexity decreases aggressive behavior in convict cichlids [Current Zoology 56 (1): 52–56, 2010]. Key words Neotropical, Life-history, Female-female competition, Fish, Resource competition Aggression in fishes can be the result of a variety of factors, including intrasexual selection, resource compe-tition, and resource defense (Ratnasabapathi et al.