Comportamento de corydoras (siluriformes, callichthyidae) em cativeiro

Abstract

The genus Corydoras comprises about 130 species of small, benthic and possibly migratory fishes. This study aims to investigate their aggregation behavior, schooling leadership, territoriality and emigration and, in this preliminary phase, recorded the behavior of populations of different species in captivity. We used populations of approximately 20 individuals each (CT= 2.5-6.0 in), respectively, of the species C. melanistius, C. juli and a third not yet positively identified (Corydoras sp.). The material, collected from streams in the municipality of Ourém, was kept in three 60x40x30 em aquaria, with substrate of gravel, submerged and floating vegetation, and pieces of logs. The variables investigated were the presence of light and the specific composition of the population present in the aquaria. It was observed that: (1) the main activities of the species include swimming displacement, substrate and vegetation investigation, individually or in groups; (2) C. juli and C sp. exhibit predominantly nocturnal activity, while C. melanistius is much more active during the day; (3) there is a gregarious tendency independent of the presence of individuals of different species and their size, even if not accompanied by subsequent activity; (4) the activity groups formed comprise from a minimum of three individuals to the entire population; (5) these groups may or may not consist of the same individuals; (6) in isolation, C. melanistius and C. juli each form activity groups, while in the other species the individuals do not group together; (7) in mutual contact, populations of C. melanistius and C. juli form mixed groups in both light and dark environments, but the third species only mixes with each of these populations in the absence of light. Larger tanks will be used in the next stage of the project to estimate aggregation patterns of these species in horizontally unlimited environments.