A selective fish mortality and some notes on Rhabdosargus sarba at Kosi Bay, South Africa

Abstract

On 6 July 2000, while crossing Lake Nhlange, the largest of the Kosi Bay lakes, several dead fish were seen, lying bloated on the surface. On investigation they were found to be large Natal stumpnose Rhabdosargus sarba. Occasionally, during twenty years of residence at the Kosi lakes, the author has seen individual Natal stumpnoses dead or dying in this lake, particularly in winter, but never so many at one time. On investigation, by questioning other local residents, it was found that the mortality had been taking place for several days and it subsequently extended for at least another 14 days.