Unmasking affiliative behavior among juvenile Midas cichlids (Cichlasoma citrinellum)

Adults of the Midas cichlid (Cichlasoma citrinellum) are predominantly normal-colored (N) morphs, although 8% in nature are gold (G) morphs. They tend to mate assortatively by color; that behavior may be influenced by prior experience with parents or siblings or by their own color. A previous experiment indicated that juveniles respond according to a rule that they avoid and behave defensively toward G juveniles and that they consort with and behave aggressively toward N juveniles (Barlow & Siri, 1987). The fear-provoking effect of G may have interfered with more subtle aspects of choice because the 4 treatment fish in each group reacted through the glass barrier to the approach of the subject. In the present experiment such feedback was eliminated by using one-way mirrors. N juveniles reared by normal parents (N X N) differentiated between N and G treatment fish only in that they attacked significantly more toward G; thus their behavior was contrary to that predicted by the fear-provoking effect of gold. The notable effect among juveniles reared by G parents (G X G) was that N spent more time with N and avoided G treatment fish, in keeping with the fear-provoking effect of gold. The results are discussed in terms of the differences in experiences between juveniles reared N X N, all of which were themselves N, and those reared G X G, consisting of both color morphs. Despite the differences in the two experiments, the main conclusion remains in place: Affiliative responses of juveniles, as measured in these tests, do not predict choice of mate among adults.