Agonistic behaviour and significance of sounds in vocalizing fish

Abstract

Vocalization during agonistic behaviour is widespread in fishes and has been described in representatives of about 30 families. Many species utter sounds when disturbed or caught, probably to startle predators. During aggressive intraspecific encounters fishes mainly vocalize while attacking or fighting, and only rarely in defense situations or when fleeing. Acoustic signals are typically accompanied by visual displays which complicates analysis of sound function. Sounds are mostly short and composed of a series of low frequency pulses. Different types of agonistic acoustic signals as in Polypterus are rare. Males are often more vocal than females but in some species e.g. cottids and gouramis sexual differences in agonistic calls are small. Agonistic vocalizations may affect outcome of contests, defense of territories, and inhibit or increase aggression. Correlation between several sound characteristics and outcome of encounters in Trichopsis vittata indicates that sound parameters are used for assessing fighting ability or motivation of rivals.