In-Vivo Assessment To Behavioural, Morphological And Melanophoric Alteratations In Response To Exposure To Mercuric Chloride In Freshwater Fish, Channa punctatus (Bloch.)

The present research focused on the acute and chronic toxicity of mercuric chloride to freshwater fish, Channa punctatus, understanding the behavioural, morphological changes and variations in melanophores. The static non-renewal acute toxicity assay was conducted by exposing the fishes to four test concentrations of mercuric chloride and 96 hr LC50 value alongwith 95% confidence limits were found to be 1.38 mg/L. The physico-chemical analysis of water was done using standard methods. The behavioural and morphological abnormalities were recorded with 8 hr observation per day during the period of 96 hr for control and exposed groups. The results showed the altered behaviour and morphological changes such as opaque eyes, erratic swimming, loosening of scales, mucous secretion and coloration changes was observed in exposed group of fishes. Three sub-lethal doses on the basis of LC50 value for chronic assay were selected (0.138 mg/L, 0.276 mg/L and 0.414 mg/L). The scales were harvested from control and exposed groups for melanophores studies by using compound microscope. The duration and concentration dependent significant variations (p £ 0.05) in the different forms of melanophores were observed and frequency of melanophores were calculated as mean ± S.E. The 5 different forms named punctate (P), punctostellate (PS), stellate (S), reticulostellate (RS) and Reticulate (R) were observed and there occurs decrease in dispersal forms of melanophores (reticulate and reticullostellate) and increase in aggregated forms of melanophores (punctate, punctostellate).