dc.description.abstract | Gross and microscopic lesions especially those associated with pollutants were investigated in Nile tilapia
(Oreochromis niloticus) and Nile perch (Lates niloticus) from Lake Victoria. A total of 104 live fish were
bought from fishermen from Homa Bay and Suba districts. During post mortem examination, lesions
observed were recorded; and kidney, gills, liver, spleen, heart, stomach, intestine and gonadal tissues
taken and preserved in 10% buffered formalin for histological processing. Gross lesions observed were
hyperemia, hemorrhages in various tissues; skin ulcers, eye opacity; cooked liver appearance, fibrosis,
gray spots and bile imbibitions; atrophied and cystic gonads; and fish skeletal deformity. Histological
lesions were gill aneurysms, kidney tubular lumen occlusions, increased melanomacrophage aggregation
in the liver, kidney and spleen; liver sinusoidal hemorrhages, fatty degeneration, hepatocytes‟
vacuolations, necrosis, bile stasis and granulomas; kidney granulomas; testicular and ovarian
degeneration and cysts; myocarditis and myositis. The liver had majority lesions that were severe in both
fish species. These lesions can be caused by variable aetiologies, including pollutants. In all, 63% of the
Oreochromis niloticus and 58% Lates niloticus had histological lesions. Further studies are required to
establish the cause of the lesions. | en_US |