Readiness to Display in the Paradise Fish

The readiness to perform species typical social displays and the readiness to startle in reaction to novel stimuli are increased in socially isolated paradise fish. Males that are kept in large, bisexual populations or have been socially isolated for a few hours show low display and low startle readiness. Reactivity is increased following 1 day of social isolation, and a further increase is obtained by prolonging the isolation up to 4 days. Males that receive continuous visual stimulation from a conspecific male or from a goldfish for 4 days show reduced display and reduced startle readiness. Social isolation appears to have general effects on behavior, increasing reactivity to various kinds of stimuli in addition to social stimuli. It is proposed that isolation-induced increases in display readiness are largely a result of the low level of external stimulation. Social isolation may or may not have specific effects on social display readiness.