An investigation was carried out on Food & Feeding and Reproductive biology of Nile tilapia Oreochromis niloticus caught from Nellore reservoir. Fish samples were collected from fish landing centres around Nellore reservoir of Andhra Pradesh from August, 2015 to July, 2016. Gut content analysis of the present study revealed that O. niloticus was found to be planktivorus comprising of mainly Diatoms, Blue green algae, Green algae, Copepods, Macrophytes, Cladocerans, Rotifers, unlike reported earlier as herbivorous and omnivorous. Percentage of highly fed, moderately fed, low fed and empty stomach of the tilapia were found to be 12.08%, 40.06%, 20.36% and 27.48% respectively. Maximum percentage of moderately fed stomachs were observed during the month of May, 2016 (51.51%) followed by July (50.92%) and December (49.65%) and empty stomachs were during September (49.22%).
Length at first maturity (Lm) was observed at total length of 189.5 mm. Higher values of ripe ovaries were observed during September (26.72%) followed by December (21.91%) and November (21.78%). Maximum maturing stage was observed during April, 2016 (53.79%) followed by May, 2016 (46.55%) and February, 2016 (43.90%). Highest matured (stage V) fish was noticed during November (28.93%). Male and Female sex ratio varied from 1:0.65 to 1:1.23 during March to September. Fecundity ranged from 1854 to 2371 eggs was observed for the ovary weighing between 8.53 to 9.14 g respectively. The stage V (mature) eggs had diameter ranging from 0.69 mm to 1.24 mm and diameter of stage VI (ripe) eggs varied from 1.19 mm to 1.55 mm. It could be concluded that Nile tilapia should be caught after attaining the size of Lm 190 mm and should not be exploited during the month of September to December since the period is peak spawning season for the Nile Tilapia in the Nellore reservoir.