Sexual behavior: social and ecological influences in the Anabantoid fish, Trichogaster trichopterus.

The influence of behavioral and environmental variables on the initiation of spawning in Trichogaster trichopterus was investigated. The behavioral responses of isolated males and females to conspecific visual and chemical stimuli were also examined. Fish in divided aquaria were administered visual cues of a conspecific through a glass partition, chemical cues by an exchange of water between the two chambers, or both visual and chemical Cues. Males and females differed in their response to stimuli from the opposite sex. In addition, responses differed with the sex of the stimulus fish. Chemical cues elicited nest building in males but not females. In the spawning experiments, when one member of a pair of fish was exchanged daily, the male spawned the first day without a nest. The female spawned only after several days. Two manipulations shortened spawning latency: introducing a new male daily and isolating the female for 3 days in the spawning aquarium prior to union with a male. Spawning was delayed, or did not occur, when the female was exchanged each day during the mating period or when a second, smaller female was kept in the spawning aquarium for 3 days prior to introduction of a male. These results suggest that the induction of spawning readiness in females is more susceptible to social and environmental variables than it is in males.