Detection of microcystins in nile tilapia (Oreochromis niloticus) from a eutrophic pond containing Microcystis aeruginosa bloom in Dhaka, Bangladesh

Cyanobacteria blooms are a very common phenomenon in eutrophic aquaculture ponds in Bangladesh. Microcystins (MCs) accumulation in different organs of the freshwater fish Oreochromis niloticus, collected from a eutrophic pond in Dhaka city containing heavy blooms of Microcystis aeruginosa were investigated using High Performance Liquid Chromatography (HPLC/MS). Among the organs tested MCs were only detected from the liver. No MCs was detected from the gut and muscle of the fish. Two variants of MCs were detected from the liver; MC-RR and MC-LF and their concentrations were 0.25ug/g and 0.22 ug/g, respectively. The total concentration of MCs (0.47 ug/g) found in O. niloticus was higher than the WHO tolerable daily intake (0.04 ug/kg). The present study suggested that the fish farms should be monitored for the presence of toxic cyanobacterial blooms to minimize the exposure of potent hepatotoxins to fish and humans through the food chain.