LEARNING OF YOUNG GOLDFISH (CARASSIUS-AUR ATUS) IN STABLE AND FLUCTUATING ENVIRONMENT

Learning performance in fishes, being variable within a species, affec ts sufficiently efficiency of their feeding and antipredator behavior. Hypotheses of the relation between learning estimates obtained during active avoidance and feeding reinforcement are tested in a number of experiments on individual screening of the goldfish sibs (24 individua ls of 2 months old). In the latter case, screening was conducted in bo th stable and fluctuating environment. Those individuals which success fully learned active avoidance, less did so in respect of searching un iformly dispersed food but was faster in searching food patch with cha nging localization. Two kinds of individuals could be recognized even among sibs: 1) those who are successful in gaining and using habits in stable environments, and 2) those who are more successful in the sear ch/avoidance in fluctuating (unpredictable) environment. These finding s are discussed from the viewpoint of optimal foraging theory and mode rn concepts of the animal searching behaviour.