Specific Individuals of Rainbow Trout (Oncorhynchus mykiss) Are Able to Show Time-Place Learning

Authors: M. SAEED HEYDARNEJAD, G. J. PURSER

Abstract: Using demand-feeders, time-place learning association of food was investigated in rainbow trout (Oncorhynchus mykiss) in 2 small raceways (TR1 and TR2). In order for the fish to be visually identified, they were tagged individually and their behaviour and distribution were monitored by cameras. Equipping with a demand-feeder, TR1 was assigned to test 2 times/1 place (2T/1P) while 2 demand-feeders were used in TR2 assigned to test 2 times/2 places (2T/2P). After 26 days of restricted feeding (RF) the fish were deprived of food for 3 days. The results of the present study indicate that, at the group level, rainbow trout are not able to clearly demonstrate time-place learning except for some fish in the group. These fish were identified as dominants, in terms of a higher rate of agonistic acts or a greater amount of food eaten. Feeding behaviour was largely influenced by social dominance of the group, especially through territoriality.

Keywords: Time-place learning, aggressiveness, social behaviour, rainbow trout

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