Effect of environmental information richness during early development of bream (Abramis brama; Cyprinidae) upon feeding and defensive behavior of its yearlings

Abstract

The feeding behavior of bream (Abramis brama) yearlings kept before the experiment (four months post hatch) under different conditions has been studied. Three variants of conditions, varied in their levels of informational richness, were modeled for keeping young fish prior to the experiments: 1—minimal richness, mimicking conditions of standard commercial hatchery containers; 2—the conditions enriched by a water current; 3—the conditions enriched by modeled impact of predation and feeding by live food. In the following experiments, the conditions were similar for all three groups. It was revealed that the fish grown under the conditions of Variant 1 had a lower learning ability, higher extent of schooling behavior, and lower efficiencies of feeding and defensive behaviors. Similar traits were described in literature as being typical for the fish grown at standard fish farms. The Variant 2 fish had the shortest adaptation period and most efficient feeding behavior but were lacking the skills of defensive behavior. The fish from the 3rd variant had a medium duration of adaptation period and efficient feeding behavior and possessed well-developed skills of defensive behavior. The results have shown that the level of environmental information richness during fish early life stages plays a crucial role in further development of the most important adaptive forms of behavior. Maintaining the young fish in containers with water current facilitates swimming performance and development of feeding behavior. However, such fish, in fact, lack the skills of defensive behavior.