Comparative analysis of biochemical components of liver and muscle of a fish, Schizothorax plagiostomus Heckel, from warm and cold water rivers near Muzaffarabad, Azad Kashmir, Pakistan

The liver and muscle of fish, Schizothorax plagiostomus Heckel, collected from cold waters of River Neelum and warm water of River Jhelum were biochemically analyzed to evaluate the physiological adaptation of the fish in the two temperature extremes. Hepatic glucose, glycogen, total lipids, cholesterol, total proteins, soluble proteins and free amino acids contents were found higher in cold water fish than in the same age groups of warm water fish; whereas, less amount of DNA and RNA was observed in cold water fis, when compared with those of warm water. Likewise, all the biochemical components of the muscles were higher in the cold water fish than those found in the warm water fish of the same age groups. These results indicate the accumulation of various biochemical components in livers and muscles of cold water fish due to low metabolic rate and less demand for energy which is because of slow movement of fish living in the cold water.