Effect of anthropogenic activities on aquaculture in north India and consequences for fish health resulting from bioaccumulation of heavy metals and histological alterations

Abstract

Investigations were carried out to assess the quality of fish Clarias gariepinus cultured at the pond in Northern India, Aligarh. The fishes are transported to fish market for multiple uses. It is indeed a matter of concern to detect Cu, Zn, Ni, Pb, Cr, Fe, Cd and Mg in both water and fish (C.gariepinus) tissues/organs (Gastrointestinal tract, Stomach, liver, Blood, Stomach content and Testes) cultured in the pond. Water and fish samples were collected from four different zones of the pond and analyzed for heavy metal accumulation. Thereafter alteration in fish tissue histology was also studied. Results obtained for water samples followed the order Ni (0.581±0.004MgL^-1)>Pb (0.570±0.006 MgL^-1)>Cd (0.110±0.001 MgL^-1)>Cr (0.077±0.009 MgL^-1)>Zn (0.075±0.003 MgL^-1)>Mn (0.065±0.004 MgL^-1)>Cu (0.054±0.007 MgL^-1)>Fe (0.052±0.005 MgL^-1). Maximum accumulation among tissues was observed in blood and lowest was observed in Integuments. Fe (1257.90 Mgkg-1.dw) concentration was recorded highest and Cd (6.68 Mgkg-1.dw) concentration was the lowest in all the tissues. Values for Bio-indices were as follows: Hepatosomatic Index (1.01), Gastro somatic Index (0.24) and Gonadosomatic Index (0.42).  Bioconcentration factor (BAF) was highest in Blood followed by stomach content, liver, testes, G.I.T., stomach and integument. Water and Fish tissues showed accumulation beyond the permissible limits given by WHO and the United States (US) guidelines. Histopathology was also noted in the form of Necrosis, Pyknosis and Vacuolization in the liver, Macrophage Infestation in the stomach, disappearing spermatocytes and tissue breakage in testes.