[Behavior of fish in groups presented with an extrapolation problem].

Grouped carps as well as isolated fishes were shown to be uncapable to extrapolate the direction of movement of an alimentary stimulus after its disappearance from the visual field. Differences in behaviour of isolated fishes and grouped ones as well as those between the groups of different size and composition were revealed in repeated performance of the same extrapolation task. Groups of six fishes exhibited higher behavioural plasticity in comparison to isolated fishes and groups of two unlearned animals: in the former orienting-exploratory activity was higher and the process of learning more stable. At minimal group size (two animals) learning was accelerated only in the case if one of the fishes had been previously learned. Some decrease in efficiency of task solving was observed in a learned fish after its grouping with unlearned one.