Unusual effect of chemical communication on social aggression in juvenile cichlid fish Cichlasoma paranaense (Cichliformes: Cichlidae)

Abstract

Some fish species are socially organized and show a social rank order which is achieved through aggressive interactions. After hierarchy is settled, such species communicate their ranks through several sensorial cues; this communication is adaptive because it reduces detrimental effects from physical contests. Cichlid fish are socially organized and signal their social ranks through visual, acoustic and chemical communication. The response to signaling may vary according to the species and environment; the knowledge of different species is fundamental to understand the evolutionary forces upon their social communication. We tested the effect of chemical signaling on social groups of juvenile cichlid Cichlasoma paranaense by renewing the water in the aquarium, a procedure that washes away chemical information and increases aggressive interactions in other cichlid species. Two treatments were designed: 50% and 0% water renewal. Aggressive interactions were video-recorded immediately before water renewal, 1min, 1h, 2h, and 24h after water renewal. The treatment with the water renewal did not increase aggressive interactions within the group. The 50% water renewal apparently reduced aggressive interactions in this species, indicating an interspecific difference on the aggressive response to chemical variation in the social environment.

Social behaviors as welfare indicators in teleost fish

“…Since chemical cues play a central role in communicating social status and regulating behavioral interactions among fish, water removal can wash out chemical substances and interfere in social rank signaling in highly social cichlids (57). In C. paranaense, water removal does not increase aggressive interactions, in contrast with evidence in P. scalare, suggesting interspecific differences on the aggressive response to chemical signaling in the social hierarchy (58,59). Changes in water temperature can also alter aggressive behavior in a species-specific manner, since a raise in temperature increases aggressive displays in Apistogramma agassizii and Amatitlania nigrofasciata (60,61), but C. paranaense reduces aggression in lower temperatures (62).…”

Physiology, endocrinology and chemical communication in aggressive behaviour of fishes

“…Studies in O. niloticus found that aggression of subordinates, but not dominant fish, was higher when their water was renewed compared with not renewed (Gonçalves‐de‐Freitas et al ., 2008). Nonetheless, in another cichlid Cichlasoma paranaense , 50% water replacement led to a reduction in aggression, suggesting the existence of species specificity in the aggressive response to chemical stimuli in the social environment (Gauy et al ., 2019).…”