The interaction between conditioned fish and naive schools of juvenile carp (Cyprinus carpio, pisces).

In a circular experimental pool the behaviour of trained juvenile carp placed in naive schools of different size and of different behavioural motivation was studied. It could be shown that the time the trained fish needed to arrive at the feeding place was much shorter when it swam in a habituated school than in a frightened one. This is discussed as a result of the conflict between the conditioned reaction and the various levels of mutual attraction. In the same manner the time elapsing from CS until the interruption of the movement of gills and fins also varied. The percentage of schooling companions which followed the trained fish to the feeding place diminished with growing school size. Six to ten fish may be the upper limit that one carp can guide.