Effects of sex ratio and feed quality on mass production of Nile tilapia, Oreochromis niloticus (L.), fry

Two experiments were conducted on Nile tilapia, Oreochromis niloticus (L.), in laboratory fibreglass tanks. The first experiment aimed to test the effects of four different sex ratios, which ranged from two to five females to one male, on mass production of fry. The lowest sex ratio (two females to one male) gave significantly the highest production, while the highest sex ratio (five females to one male) gave the lowest. The objective of the second experiment was to compare the effects of different diets which varied with regard to feed components (natural versus artificial). The diet composed of animal-plant protein (the standard artificial diet) in addition to natural food (65% phytoplankton and 35% zooplankton) gave significantly the highest fry production and the highest breeders’growth. Exclusively standard artificial diet gave significantly better fry production and better breeders’growth over the rest of tested diets except the above-mentioned one. The addition of natural food to the artificial diet enhanced fry production as well as the breeders’growth, and the better the quality of the artificial feed, the better the results obtained.