Colour variation in Sperata sarwari population inhabited in the indus drainage system

Fish has great tendency to adapt the environmental variations due to alteration in the physico-chemical quality of water. The colour variation indicates the phenotypic variations among and between the fish population found in different geographical regions. Therefore, this study was conducted to observe the colour variations among and between Sperata (S.) sarwari populations inhabited in the Indus drainage system. Fish samples (54 individuals) were collected from different geographical regions of four rivers (Chenab, Jhelum, Ravi and Indus). The body and adipose fin colour of all samples were observed and compared to investigate the colour variations among all individuals. The body colour of S. sarwari varied in different geographical regions due to predatory habit of fish. Body colour varied from dark grey colour to light grey colour on dorsal side while silver white colour on ventral side. Colour of fleshy adipose fin also varied from dark grey to light grey with and without black margin while position and colour of spot was the same in all individuals of S. sarwari. The 25% of total samples showed colour variation in adipose fin. The 50% individuals inhabited in the up and downstream of the River Indus and downstream of the River Jhelum showed the light grey colour of adipose fin with no dark grey margins, while individuals with black margin of adipose fin showed the lowest percentage (9.25%). It was concluded that the phenotypic colour variation of S. sarwari was influenced by environmental condition of rivers and predatory habit of fish.