Feeding-site utilization in three sympatric species of Petrotilapia (Pisces, Cichlidae) from Lake Malawi

Abstract

Three sympatric sibling species of Petrotilapia, with similar dietary and macrohabitat requirements, occur near Monkey Bay, Lake Malawi. Males and females of all three species fed selectively on the rocky shores. Males utilized less than 6% of the space they defended as a breeding territory for feeding and although interspecific overlap of territories was considerable, only 2.5% of the feeding space used by territorial males was shared. Males primarily utilized rich food patches which occurred within the territories of highly aggressive Pseudotropheus species, whereas females tended to feed in undefended areas. Although Petrotilapia species are not highly aggressive fishes, there was a well-defined social dominance hierarchy amongst them and it is suggested that feeding-site utilization is dependent on social rank. Inter-and intraspecific differences in feeding-site utilization probably facilitate species coexistence and thus contribute to the maintenance of the high species diversity which is a characteristic of the ichthyofauna of Lake Malawi.