Effect of Zinc Toxicity on Histological Changes in Brain and Gonad of Goldfish, Carassius Auratus

By : A. Subburaj , T. Francis , N. Jayakumar , P. Elakkanai

Page No: 53-61

Abstract
The present study was carried out to find out the toxicity effect of Zinc and histopathological changes in the brain and gonad of goldfish (Carassius auratus) under acute and sub-lethal concentrations of zinc. The LC50 values of C. auratus exposed to Zinc were calculated by Probit Analysis and the mean LC50 value were 108.05, 69.15, 38.002 and 22.89 mg.l-1 at 24, 48, 72 and 96h respectively. The histological changes were studied in the brain and gonad of the treated fish. Vacuolation, increased in size of nucleus, hemorrhage, binucleated nucleus, hyperplasia and necrosis, degenerated nucleus, ruptured nucleus and increased in number of nucleus were observed from the brain of treated fish. Rupture of seminiferous tubules, vacuolation, blood congestion, degenerated seminiferous tubules, reduction of spermatocytes, reduction of spermatozoa and reduction of spermatid were observed from the gonad (testis) of treated fish. Atretic follicles appeared, ruptured ovarian wall, shrinkage of oocytes, degeneration of egg envelops, immature oocytes, enlargement of oocytes and increased number of atretic follicles were observed from the gonad (ova) of treated fish. Above results showed that exposure of fish to different acute and sub-lethal concentration of zinc made changes in their internal organs (brain and gonad) of goldfish, Carassius auratus. This confirms the possibility of zinc to be a toxicant even at lower concentration.

Authors :
T. Francis, P. Jawahar, N. Jayakumar and P. Elakkanai
Department of Fisheries Biology and Resource Management, Fisheries College and Research Institute, Tamil Nadu Fisheries University, Thoothukudi - 628 008, India.