Abstract
The present study evaluated the effects of water pollution on Cirrhinus mrigala in the Ravi River by comparing DNA extracted non-invasively from their scales to DNA extracted from the scales of fish collected from controlled fish farm. A single, random sampling was conducted. Fish were broadly categorised into three weight categories: W-1 (500 to 1000 g), W-2 (1001 to 1500 g) and W-3 (1501 to 2000 g). DNA was extracted non-invasively from control and experimental samples. The quantity and quality of DNA from the control and experimental samples were compared. The experimental samples in the W-1, W-2 and W-3 categories had an average DNA concentration (mu g/mu l) that was lower than the control samples. All control samples had a single DNA band; whereas the experimental samples in W-1 fish had 1 to 2 bands, the experimental samples in W-2 fish had two bands and the experimental samples in W-3 fish had fragmentation in the form of three bands. These bands show the effects of pollution on fish in the Ravi River. We concluded that this non-invasive assessment tool could be successfully used in scale-bearing fish species for assessment of contaminants and damage in the DNA as a rapid, non-lethal and biologically reliable indicator of water quality for the presence of various toxicants in surface water and their effect on the fish health.