Influence of previous experience on the mate selection of two colour morphs of the convict cichlid, Cichlasoma nigrofasciatum (Pisces, Cichlidae).

In a pilot test, individuals of two colour morphs of Cichlasoma nigrofasciatum showed colour preferences in their schooling behaviour according to previous experience. Two further experiments were undertaken to investigate if such experientially induced preferences could reflect on the choice of mate. In one experiment white males who had been reared differently with regard to the colour morph of parents and siblings were given females of the different colour morphs (white and normal) to choose from, the females being successively removed after pairing to induce further choices. In this test, however, the males predominantly chose normal females, probably because of dominance relationships among the females, which masked a possible colour preference. Instead, a free choice test was devised, where 74 white and 74 normal fishes were allowed to pair off freely in a large tank. Here, a statistically significant sexual preference for the previously experienced colour morph was found. These results, as well as the possible evolutionary consequences, are discussed.