Filial Imprinting in the Convict Cichlid Fish Cichlasoma Nigrofasciatum

Abstract

The convict cichlid fish, Cichlasoma nigrofasciatum, exhibits extended parental care in both the laboratory and the field. Families of this species were observed in Lake Xiloa', Nicaragua, during part of the breeding season. Young fry (less than 5 days free swimming) could be induced to follow a variety of "dummy" parents when their own parents were restrained at a distance. Older fry fled the dummies in the same manner as they fled predators. Two laboratory experiments were conducted to analyze further the responses of convict cichlid fry to parental dummies. Experiment I demonstrated the following: 1. Fry showed consistent preferences in tests with 5 pairs of mechanically moved dummies. Some of these preferences involve species characteristic cues. 2. Responsiveness to dummies increased over time within a test and over repeated tests. Responsiveness changed non-monotonically with age; those tested at 1 to 3 days free swimming were most responsive, 6 to 8 day old fry were least responsive and 14 to 16 day old fry showed intermediate responsiveness. 3. Preferences were weaker in the older, less responsive fry but were generally in the same direction as in younger fry. Experiment II tested the effects of experience with a particular dummy on the preferences demonstrated in Experiment I. For all ages and for most dummy pairs there was a significant interaction between training condition (preferred vs non-preferred dummy) and preference. Experience with a single dummy also resulted in a general increase in responsiveness to the two dummies in the preference test. The present results are discussed in terms of selection pressures presumed to operate on natural populations of C. nigrofasciatum and also in terms of research on "imprinting" in precocial birds.