Comparative Study between the Performances of Nile Tilapia Oreochromisniloticus during and Out of the Normal Spawning Season

Abstract

During the production season (2010-2011), this work was carried out at a commercial tilapia hatchery in Motobas, Kafr El-Sheikh Governorate- Egypt. Two experiments were managed using the same design to make a comparison between spawning of Nile tilapia Oreochromisniloticusbroodstock off-season (the winter) and on-season (the summer). The two experiments were tested by studying the effects of using feed additive (Nuvisol hatch P® 0.1%), different broodstock sizes (350, 200, 150 and mixed up to 250 g/fish) and stocking densities (50, 55, 60 female/pond-24m2) on growth performance, feed utilization, reproductive performance and economical profitability parameters of Nile tilapia, O.niloticus spawned in the summer and in the winter. Comparing the results of the economic analysis of the two experiments showed that the total production of Nile tilapia fry per each spawning pond, 24 square meters, is 28,090 within the natural spawning season, an increase of 2.23% from that was spawning outside the normal season (27478 fry). Though total revenue and net income under hatchery conditions in the out off-season (February 2010) much higher than that in natural spawning season (April 2011) by 22.01%. This is of course due to the price of tilapia fry in the winter months is higher than the summer to supply shortages in winter and increased demand at the same time. This is due to the farmers need to start the growing season early, March/April, in order to harvest their fish before temperatures drop in the next winter, which adversely affect the life of the fish.