The objective of this study was to follow up the growth performance and gonads development of sex reversed male Nile tilapia. Fish fed commercial diet contained 30% crude protein at a rate of 3% of the biomass and 10 fish were randomly taken biweekly during the experimental period (16 weeks). Growth performance, feed utilization and survival rate were calculated. Histological examination of the gonads was done every two weeks to follow the growth and development of the gonads. Results showed positive interactions between growth parameters and reproductive development during different periods of fish productive cycle. Histological examination illustrated that during early ages, testicular sections of mono sex male’s tilapia had abnormal architecture with deterioration of germinative tissue. Despite abnormal testis texture, fish started spermatogenesis, a step toward puberty when their body weight reached 29.16g. As fish reached 4-5 months, male start to recover their testes normal structures and at age of 5.5-6 months, testicular sections appeared normally as pointed out by firmed testicular lobules, existence of all germ cell types and the intensively stored spermatozoa in testicular lumen and testicular ducts, confirming the full maturity of males. Based on the obtained results, it can clearly conclude that there is a relationship between age, body weight and development of sexual glands. It has also been shown that the hormonal treatment of tilapia seeds in the early stages for production of mono sex (all males) leads to a marked deterioration in the testes structure, continues near the fish enters the sexual maturity. At a later age, males can overcome this deterioration, restore the histological  structure of the testes and achieve full sexual maturity at the age around from 5.5 to 6 months.

The aim of this study was to investigate the use of corn distillers dried grains with solubles (DDGS) (27.11% CP) and Foots (20.84% CP) as corn processing by-products in monosex Nile tilapia, Oreochromis niloticus diets to replace yellow corn as an energy source and its effect on growth performance, nutrients utilization, whole body proximate composition, nutrients digestibility and economic efficiency. Three hundreds and seventy five fingerlings of Nile tilapia (10± 0.05 g) were randomly distributed into 15 circular plastic tanks (1000 L), representing 5 treatments. Isonitrogenous (25 to 25.84%) and isocaloric (4174.79 to 4364.65 Kcal GE/kg) experimental diets were prepared with substitution levels of DDGS 0% (T1), 20% (T2) and 40% (T3) and Foots 20% (T4) and 40% (T5). The experimental period lasted for 18 week. Results showed that both of DDGS and Foots have higher in all measured amino acids content than those in yellow corn except cysteine. Moreover, DDGS and Foots have higher content of linoleic, oleic, stearic and palmitic acids than those in yellow corn. Also DDGS and Foots covered the nutrient requirements of the essential fatty acid linoleic (18:2 ω 6) for Nile tilapia. Feed intake was significantly decreased as corn partially replaced by Foots more than the DDGS. Apparent digestibility coefficient of CP, EE, NFE and energy recorded the highest values for the T4 (75.76, 89.86%, 57.48 and 68.71%), respectively, followed by T3 with significant differences. The increasing in substitution levels of yellow corn by DDGS did not significantly (P˃0.05) had an effect on Nile tilapia performances. However weight gain and specific growth rate SGR were gradually decreased with increasing the substitution levels of Foots. The CP content of Nile tilapia carcass was significantly increased with increasing the substitution levels of DDGS (T3) and Foots (T5). Feed conversion ratio (FCR) of the fish fed diets T4 (20% Foots) was the best followed by T5 (40% Foots). The cheaper feed cost gain was obtained from T5(40% Foots) followed by T4(20% Foots).

The purpose of the research was to illustrate the effects of feeding Nile tilapia fingerlings (Oreochromis niloticus) with low doses of aflatoxins (AFs) with and without vitamin C supplementation to investigate the capacity of vitamin C in detoxification. Ten experimental diets were formulated and divided into three categories. The first category included: T1, T4 and T7 feedings included 20, 40 and 80 μg AFs kg−1 feed respectively, while both the second category T2, T5 and T8 and the third category T3, T6 and T9 were treated with contaminated feed with AFs for 57days then both categories shifted to different regime till the conclusion of the experimentation. The second category was fed uncontaminated feed while the third category was fed a supplemented diet with 100 mg Kg-1 of vitamin C. For 113 days the experiment was conducted. The results showed that shifting from a contaminated diet to an uncontaminated diet (category 2) or adding vitamin C to the contaminated diet (category 3) improved the deterioration that occurred in the values of growth performance, biochemical parameters and histological disorders caused by AFs. Furthermore, the results from the control group were superior to all the treatments.