Study on the seasonal variation in the chemical composition, hematological profile, gonado-somatic index and hepatosomatic index of snow trout, schizothorax niger from the freshwater dal lake, Kashmir

Abstract

Objective: The aim of the present study is to work out the seasonal variations in the hepato-gonadosomatic indices and hemato-biochemical composition of snow trout, Schizothorax niger in order to provide season wise nutritional status of the fish. Methodology: Live fish, S. niger were collected from fish market in early morning and brought in plastic containers to wet-laboratory and were stocked for overnight in 75 L plastic trough fitted with continuous flow-through system. Blood sample was collected from the caudal vain using disposable heparinized syringes for hematological analysis, later on fishes were sacrificed for biochemical analysis. Results: In the present study, the substantial differences in hemato-biochemical composition of S. niger between the seasons were observed. Significantly (p<0.05) higher moisture content (76.86%) was found in winter, maximum protein (17.53%) and fat (5.56%) contents were recorded during summer and the higher ash content (3.20%) was observed in winter. While lowest nitrogen free extract content was reported during summer. The maximum hemoglobin content (9.82 g dL-1) was found during summer and lowest (7.10 g dL-1) Hb content was reported during winter. Significant (p<0.05) increase in red blood cell counts (2.28×106 mm-3) was noticed in summer and the lowest RBC count (1.24×106 mm-3) was reported in winter. The haematocrit (HCT) content (39.07%) was found highest during summer and lowest HCT (24.29%) content was noted during winter. Significantly (p<0.05) higher WBC count observed in summer (9.46×103 mm-3) while lowest WBC count (4.68×103 mm-3) was observed in winter. The maximum value (57.13 pg cell-1) of mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration (29.25%) contents were recorded during winter. Significantly (p<0.05) highest hepatosomatic index (HSI) content (6.99) was observed in autumn, whereas no significant (p>0.05) difference in HSI was found among the remaining three seasons. The maximum gonadosomatic index (GSI) value (17.93) was recorded during spring followed by winter (15.41). While significantly (p<0.05) lowest (10.48) GSI was noticed during autumn. Conclusion: The results suggest that S. niger is very rich in protein and fat content and promises to be a favorable prized food fish. Thus its conservation and culture should be encouraged.