Estimation of microcystins in the freshwater fish Oreochromis niloticus in an Egyptian fish farm containing a Microcystis bloom.

Microcystins (MCYSTs) that accumulated in different organs of the freshwater fish Oreochromis niloticus, collected from a fish farm in Egypt containing heavy blooms of Microcystis aeruginosa, were investigated using an enzyme-linked immunosorbent assay (ELISA). The distribution of MCYSTs in the organs varied significantly. The highest MCYST level was recorded in the guts (821 ng/g fresh weight), followed by the livers (531.8 ng/g) and kidneys (400 ng/g). Smaller amounts of MCYST were detected in muscles (102 ng/g). The present study suggests that fish farms should be monitored for the presence of toxic cyanobacterial blooms to minimize the exposure of fish to potent hepatotoxins. Copyright 2003 Wiley Periodicals, Inc. Environ Toxicol 18: 137-141, 2003