Influence of Water Temperature on Physiological Functions and Histology of Crucian Carp, Carassius carassius

The present study was conducted for forty-five days to check the effect of water temperatures on hemato-biochemical parameters and histopathology of gills and liver of Crucian carp, Carassius carassius. Two hundred fishes were randomly stocked in five treatments each with four replicates in 72 litre tanks. Five treatments namely T1, T2, T3, T4 and T5 were maintained with water temperature of 16°C, 20°C, 24°C, 28°C and 32°C respectively. The hemoglobin, hematocrit and Total Red blood cells increased with the increase in acclimation temperature. Whereas, total leukocyte count showed an inverse trend. Differential leukocyte count showed significant (P<0.05) increase in neutrophil and drop in lymphocyte count. Minimum glucose level was observed at T3. Total-protein, albumin and globulin increased with the increase in temperature. whereas, Triglycerides and cholesterol showed inverse trend. The histological examination revealed that gills and liver were adversely affected below T3 and above T4, with most marked changes noticed at 32°C (T5). This fish displayed adaptive physiological changes to counteract the effect of temperature variations. The findings of this study indicate that C. carassius can be reared between 24°C to 28°C and is important for understanding how fish adapt to temperature changes, especially in context of climate change.