Agonistic Behavior and Acoustic Communication

Sounds are uttered in agonistic contexts by representatives of 30+ families of fishes but this number mainly reflects the scientific expenditure and less so the actual distribution of soundproducing families. Sounds are emitted in numerous contexts: distressful or disturbancesituations, e.g. being attacked or grabbed by predators, competitive feeding, and competition for space and sometimes mates. During dyadic contests, acoustical displays are part of a complex, signaling system, which includes visual and acoustical displays as well as physical fighting (biting, mouth-wrestling, ramming). Sounds are primarily uttered by the attacking animal during brief, intraspecific encounters or by both opponents during long contests and seldom by fleeing or submissive individuals. A small number of experimental studies on the functional significance of sound production has shown that sound production can influence the course of the agonistic interactions, although the observations and interpretation are sometimes contradictory. The most likely explanation is that the acoustic signals help to assess the fighting ability of opponents and thus decide contests before they escalate to more costly phases (damaging combat). The ontogenetic development of sound production and agonistic behavior has been studied thus far in only a single species, the labyrinth fish T. vittata. Results showed changes in sound characteristics as well as the sequence of behavioral patterns.