Geflügel, Fischerei und Wildtierwissenschaften
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Abstrakt

Age and Growth of Commercially Exploited Fish Species, Oreochromis niloticus (Linnaeus, 1758) from the Tributary of the Ganga River, India

Neeti Mishra1*, Amitabh Chandra Dwivedi2

Studies were carried out during the period February 2019 to 2020 January from the lower stretch of the Tons River at Prayagraj, Uttar Pradesh, India. During the present work, 683 fish specimens of Nile Tilapia, Oreochromis niloticus (336 males and 347 females) were studied for estimation of age composition, age and growth increment. An over-all representation of age, growth increment and age composition of O. niloticus has been obtained by the study of its key scales. The age composition of O. niloticus varied from 0+ to 7+ age groups. The maximum growth increment was recorded during first year of life cycle and showing a gradual decrease in growth as the fish got older. The minimum growth increment was recorded during the seven years of the life cycle. On the basis of pooled sampled specimen in the length ranges from 83 to 463 mm showed that the fish achieved the mean length 159 mm in 1+, 237 mm in 2+, 309 mm in 3+, 357 mm in 4+, 394 mm in 5+, 429 mm in 6+ and 455 mm in 7+ age groups. The growth increments 
  in O. niloticus was observed as 159 mm, 78 mm, 72 mm, 48 mm, 37 mm, 35 mm and 26 mm for 1+ to 7+ age groups, respectively. The slow growth increment observed after first year may be attributed to the maturity attained within first year of life. It is well known that the growth potential is used for the gonad development. The growth percentage varied from age to age in the male, female and pooled samples.