Social modification of agonistic behaviour in fish

Green sunfish were paired on the basis of size and frequency of attack behaviour, as well as coloration changes, recorded during observation sessions held over a 3-day period of time (pre-conditioning period). On the basis of attack frequency, a fish in each pair was designated as dominant while the other fish was classed as submissive. During the second phase of the study (conditioning period), which lasted for 5 days, dominant fish in group I were paired with larger fish while the submissive fish remained in isolation. In group II, dominant fish remained in isolation while submissive fish were paired with smaller fish. In group III dominant fish were paired with larger fish and submissive fish with smaller, while in group IV the dominant and submissive fish were placed in isolation during the conditioning period.Following the conditioning period, the fish were re-paired and observations of attack behaviour were made (post-conditioning period). The results suggest that the most important factor in determining whether dominance reversals will occur is the experience of the dominant fish during the conditioning period.