CONDITION AND FECUNDITY OF TRANSLOCATED ROCK-DWELLING CICHLID FISH INLAKE MALAWI

The condition factor and fecundity of the translocated sock-dwelling c ichlid fish, Cynotilapia afra, Pseudotropheus callainos, and Pseudotro pheus tropheops 'red cheek' at Thumbi West Island, southern Lake Malaw i, were compared with those at their sites of origin, in the north of the lake. The guiding hypothesis was that these species, having origin ated from a region of the lake which is generally poor in nutrients, a nd been introduced to an area richer in nutrients, would be in better condition and more fecund there than at their sites of origin. That se emed to be the case. P. callainos and P. tropheops 'red cheek' had sig nificantly higher condition factors and fecundity indices at Thumbi We st Island than at their sites of origin. However, both condition facto r and fecundity of all the species studied fluctuated seasonally. The major peaks in condition factor coincided with either the wind-induced lake upwelling from June to August, or the rains. Major peaks in fecu ndity occurred at the end of the rainy season, between February and Ap ril, or at the end of the upwelling period between September and Octob er. The translocated species began to breed at a smaller size at their sites of origin in the north than at Thumbi West Island, probably as an adaptive response to a poor nutrient regime in the north. The incre ase in population of some translocated species can be partly attribute d to their improved condition and fecundity due to enhanced nutrient a vailability at the site where they have been introduced. This may have negative implications for the native taxa, more particularly as compe tition for breeding space is rife among the rock-dwelling cichlids of Lake Malawi.