Age, Growth and Age Pyramid of Exotic Fish Species Oreochromis niloticus (Linnaeus 1758) from the Lower Stretch of the Yamuna River, India

Random samples were collected monthly from August 2011 to July 2012 for determination of age, growth and age pyramid of Oreochromis niloticus from the Yamuna river, India. Age of O. niloticus varied from 0+ to 6+ age groups. It was observed that the fish attained the mean length (pooled samples) 16.96, 24.33, 31.12, 36.44, 40.54 and 43.50 in 1+ to 6+ age group, respectively. The growth increment in O. niloticus was recorded 16.96, 7.37, 6.79, 5.32, 4.10 and 2.86 for 1+ to 6+ age groups, respectively. It is obvious from the present observations the aquatic environment of the Yamuna river at Allahabad was favorable to O. niloticus, and for the reason growth was good. The urn shaped age pyramid was recorded.