Social facilitation of acoustic training in the common carp Cyprinus carpio (L.)

Social facilitation of learning to associate acoustic signals with food was studied in the common carp Cyprinus carpio (L.). Fish were trained to associate a 400-Hz pure pulsed sound with food, by classical conditioning, in the presence or absence of trained fish ('teachers'). In the first experiment, the response to the acoustic signal of 20 naive fish, trained by themselves was compared with that of 15 naive fish trained together with five teachers in 18 training sessions. When an acoustic signal was generated, naive fish trained with teachers approached the feeding trays earlier than those trained by themselves. The difference between the two types was highly significant on the first 2 days, diminished during the following days and became non-significant on the last 2 days. Qualitative observations revealed that during the first training sessions the teachers swam from the school to the feeding trays and back, thus stimulating the naive fish to follow them to the feeder. In the second experiment, naive fish were trained for 2 days in the presence or absence of teachers. The five teachers or five naive fish were then removed from their respective groups and the remaining fish continued to be trained for 5 days. The responses of the naive fish in the two group types were similar, probably because of handling stress and/or insufficient time for learning-consolidation. This study demonstrated the occurrence of social facilitation of training to acoustic signals.