INTRASPECIFIC BROOD-MIXING OF THE CICHLID FISH PERISSODUS-MICROLEPIS IN LAKE TANGANYIKA

The frequency and origin of intraspecific brood-mixing in the biparental cichlid fish Perissodus microlepis were investigated by the cohort analysis of schooling young and the underwater observation of guarding parents. The cohort analysis showed that brood-mixing started from the early guarding state when the young were smaller than 10 mm standard length and nearly all schools of young larger than 16 mm contained alien young from up to 6 broods. Brood farming-out of this fish, which was originally proposed to be a way adopted only by a deserted parent, was performed also by paired parents. We suggest that brood-mixing in P. microlepis is attributed mainly to brood farming-out by paired and deserted parents.