Linear morphometric phenomenon of Oreochromis niloticus in the polluted location of the Vavuniya tank, Sri Lanka.

Abstract

Vavuniya tank is a perennial water body, which plays an important role in inland fisheries. This tank is extremely vulnerable to pollution, as it is located in the iya urban area. Biological Oxygen Demand (BOD) of Vavuniya tank was mined during wet and dry seasons from March 2013 to March 2014 in four locations ree replicates in order to define the polluted (3.80-4.50 ppm) and non-polluted -1.90 ppm) locations. Linear morphometrics and sex ratio of Oreochromis niloticus analyzed in the polluted (n=50) and non-polluted (n=45) locations in various ons separately. The mean values of total length, standard length, head length, eye er, snout length and depth of fish from polluted location were significantly (p<0.05) than that from non-polluted locations. In regression analysis, log standard lengths other length logarithms were plotted and graphical out-put showed positive linear nship in both locations. However, two females in the polluted location showed ely larger eye diameters (2.1 and 2.2 em). Hence, this needs further investigations. agh the number of males was higher than that of females in the samples; it did not any significant differences. Though the oil and grease contamination was very high polluted location (30+5 ppm), presence of O.niloticus indicated the resilience nature howed higher linear morphometric phenomenon. However, undesirable kerosene in the fish reduced the revenue.