Impact of pre-aggressive experience on behavior and physiology of black rockfish (Sebastes schlegelii)

Social dominance can cause growth heterogeneity of fish in captivity, but little is known whether pre-aggressive history can change fish behavior and physiology after facing a new encounter. This study investigates the impact of the pre-aggressive experience of black rockfish (Sebastes schlegelii) on the outcome of a subsequent aggressive interaction in fish with four pre-aggression histories. After fighting with a different-sized opponent in a paired-fish arrangement, the manipulated winners demonstrated more pendulum attacks, while the manipulated losers reduced the winning rate, increased the latency period of the first attack, and had a higher level of cortisol when facing a new encounter. These results indicate that the aggression of black rockfish was impacted by pre-aggressive experience in a subsequent aggressive interaction. However, once encountered new opponents, the mirror fighters that were involved in aggressive interactions but did not experience either a victory or a defeat had similar behavioral and physiological characteristics to those in the control group. We conclude that social defeat may play a role to suppress aggressive behavior in black rockfish. Our results add to a new understanding of farmed fish aggression and could help the improvement of behavioral management in intensive fish farming.