The present study was carried out to observe the histopathological changes in the brain and testis of goldfish (Carassius auratus) under sub-lethal concentrations of copper. During the experimental period of 28 days, a total of five sub-lethal concentrations (0.014, 0.028, 0.056, 0.112 and 0.223 ppm) were tried and samples were collected on 14th and 28th day. Among the five concentrations, the tissue samples of brain and testis were collected from 0.056 ppm (3rd concentration) and 0.223 ppm (5th concentration) and compared with control fish. Histological slides were prepared following the standard histology procedure developed by Humason (1972).
Ruptured nucleus, enlarged pyramidal cells, vacuolation, degenerated nucleus, necrosis, hemorrhage and hyperplasia were observed from the brain of fishes treated with Cu. Reduction of spermatid & spermatozoa, separation of boundary membrane, blood congestion, enlargement of spermatozoa, hyperplasia, reduction of spermatocyte, reduction of spermatogenic masses and degenerated seminiferous tubules were observed from testis collected from fishes treated with Cu. The extent of alterations in the brain and testis was observed to vary with the concentrations of Cu. But the histology of brain and testis collected from control fishes showed normal type of cells.
Above results showed that exposure of fish to different sub-lethal concentrations of copper made changes in their internal organs (brain and testis) of goldfish, Carassius auratus. This confirms that copper has the potential to make alterations in the tissues even at sub-lethal concentrations.