E ight experimental diets representing two levels of vitamin E (low 100 IU /kg diet and high 300 IU/kg diet) with four levels of selenium (0;2 ; 4 ; 8 mg/kg diet) were tested on hybrid tilapia (-Qr-niloiieusX JX~mweu8~) for a period of 120 days. "The study was performed in outdoor cement ponds, each divided to units by nets with an area of 10m each. Each treatment was performed in duplicates, using 40 experimental fish with an initial weight of 48.83 g on the average. After the adaptation period, the fish were fed on the experimental diets at a rate of 3% of the treatment bibmass dialy, divided into two equal portions at 10. 0 a.m and 2 p.m. Water temperature ranged between 28J to 3L5 °C during the experimental period. Water quality parameters (dissolved oxygen, ammonia oED were within the permissible levels for tilapia. Results obtained^ surhmenzed/in the followingr 1-Hybrid tilapia fea on 2mg Se with 300 IU vitamin E/kg diet had significantly higher (p < 0.05) specific growth rate (SGR), feed conversion efficiency and also improved feed conversion ratio than that fed on the other diets. 2-At constant dietary vitamin E level, total serum protein increased with increasing Se level up to 8 mg/ kg diet. 3-Fish fed on high level of supplemented vitamin E (300 IU/kg) diet without selenium deprivation, showed increased growth rates and 54 Ahmed K. I. El-Hammady et al. improved feed conversion rate than that fed on the low vitamin E (lOOIU/kg dry diet). 4-The histological investigation showed remerkable effects in the liver tissue of hybrid tilapia fed on dietary Se-supplemented level up to 8mg/kg diet with low vitamin E (lOOIU/kg dry diet) with different degrees of injuries, including blood vessels, hemorrhages and degeneration in hepatic cells, dilatation, odema and hemosidren, hemolysis, necrosis and activation in nuclear division. This study suggests that supplementation of Vit. E 300IU/kg with selenium up to 2 mg / kg dry diet for hybrid tilapia is warranted to increase growth rate and prevent fish from increased concentration of waterborne Se up to toxicity levels.

A total of 120 meagre, Argyrosomus regius, larvae (0.37 ± 0.02 g) were assigned to four treatments (three replicates each) to determine the optimum dietary level of PUFAs, at which there will be the best growth performance, feed utilization, fatty acids composition and antioxidant status. The treatments were a control group (fed a basal diet 3% PUFAs of total fatty acids) and another three groups fed PUFAs supplemented diets at levels 4.55, 6% and 7% for 21 days. The results indicated that increasing dietary PUFAs levels up to 4.5% significantly improved growth and survival compared to the control group. Feed intake, feed conversion ratio and protein utilization were significantly increased with 4.5% PUFAs followed by the control group. The results revealed significant differences in PUFAs among treatments and the best value was reported for the 4.5% PUFAs supplemented diet followed by the control. There is a significant increase in TBARs levels with increasing dietary PUFAs concentration. Meanwhile, the SOD and CAT activities decreased significantly with increasing PUFAs levels. However, TAS decreased significantly with higher PUFAS level (6%) only compared to other treatments. Therefore, the dietary requirements of A. regius larvae is 4.5% PUFAs of total fatty acids.

Keywords:Mugil cephalus Protein Energy Lipid Carbohydrate growth performance feed efficiencyThe effect of varying dietary protein and energy levels on the growth performance, feed efficiency and tissue chemical composition by increasing dietary energy sources (lipids and carbohydrates) for flathead grey mullet, Mugil cephalus fingerlings were evaluated. Twelve experimental diets were formulated by four different dietary protein levels (25, 30, 35 and 40) combined with three different gross energy levels (16, 17 and 18MJ/kg diet) to provide 12 different dietary protein: energy ratios (15.43, 14.40, 13.64, 18.60, 17.46, 16.42, 21.63, 20.73,19.20, 24.26, 23.02 and 21.79 MJ/kg diet). The present results showed that, the highest final body weight, weight gain, specific growth rate, feed efficiency and protein efficiency ratio values were recorded with increasing of dietary protein levels from 25 up to 35%, irrespective of dietary energy levels. However, irrespective of dietary protein levels, the increasing dietary energy levels (from 16 to18 MJ/Kg diet) obtained slightly final body weight, weight gain, specific growth rate, feed efficiency and protein efficiency ratios. Feed conversation ratio values decreased (P≥0.05) either with increasing dietary crude protein or dietary energy levels. The best FCR value was recorded with dietary energy 18 MJ/kg and 35% protein. No statistical differences (P>0.05) were observed for the effect of dietary protein energy ratios on whole body proximate analysis except for body ether extract contents. The body lipid deposition may indicate that, when dietary lipid was supplied in excess, a proportion of this lipid was deposit as fats. Concomitant increase (P<0.05) of body lipid and protein retained were observed with increase dietary lipid levels, while negative effect on energy retained was recorded with increase energy levels. These results suggested that the diet contains 30% crude protein with 18MJ/kg -1 gross energy enhanced the growth performance and feed efficiency of Mugile cephalus, had protein-sparing effect and increased the utilization of each dietary protein and energy sources.

he Efficacy of replacing fish meal with fish waste meal, crayfish meal and gambusia fish meal on an ideal protein basis in diets for African catfish, Clarias gariepinus , were evaluated under production conditions in concrete ponds. African catfish averaging 325.21±3.99 were randomly distributed among twenty outdoor concrete ponds subdivided (partitioned) by netting to 20 rearing units representing the twenty treatments studied. Each unit was 4.0 m length, 2.5m width and 1.0 m depth (10 m 3 ) freshwater at a stocking rate of 25 fish per rearing unit. Ten experimental diets isoprotein (37%) and isocaloric diets (19KJ /g) were formulated to contain three (3) animal source protein (Fish waste meal, Crayfish meal and Gambusia fish meal) at three (3) level of substitute of fishmeal (50, 75 and 100%) and control diet in the experimental design .After 16 weeks (112 days), feed conversion efficiency and protein efficiency ratio decreased significantly (p<0.05) with increasing dietary fish waste meal substitution for fishmeal. The growth parameters indicated that weight gain, specific growth rate decreased significantly with increase in crayfish meal. The fish diet containing gambusia fish meal (75%) and control diet had significantly (p<0.05) higher weight gain, specific growth rate compared to other treatments. Based on the observed results, either of the tested products can be used to reduce the fishmeal content, when fish waste meal was available, 50% fish waste meal serviced as assailable partial replacement for fishmeal, though with crayfish meal was available the replacement of 50% of the fishmeal in basal diet African catfish with crayfish meal. However, the 75% gambusia fish meal in the present study is a suitable complete substitute for fishmeal in practical diets for African catfish. When three source of animal protein were availability, the gambusia fish meal (75%) a suitable substitute for fishmeal in practical diets for African catfish (Clarias gariepinus).

wo experiments were performed in two or three way factorial design on Nile tilapia hybrid (O. niloticus x O. aureus) at the El kanater El khairyia Experimental Fish Research Station belonging to NIOF. The three experiments were carried out in outdoor concrete tanks, each of 10m 3 total water volume. Both experiments lasted 20 weeks after start and fish initial weights for the first and second experiments were 30.24 and 31.76 g, respectively. The first trial aimed to test the interaction between protein (25 or 30 % p25 or p30) and dietary energy levels (15.70; 16.74 or 18.84 Kj g-1 dry diet) on growth performance of hybrid tilapia. In the second experiment, three feeding rates (2, 4 or 6% biomass of fish R2 ;R4 or R6) within each rate two feeding frequencies (2 or 3 times /day F2 or F3) within each two stocking densities (25 or 50 fish /m 3 D25 or D50) were tested for their effects on growth performance of hybrid tilapia. Results of the first experiment revealed that the maximum growth performance of hybrid tilapia was obtained using the diet P25% E16.74KJ, which is recommended for hybrid tilapia. Results of the second trial recommended the feeding rate; frequency and stocking density of 4%; two times feeding at 25 fish/ m i density, respectively for best growth performance of hybrid tilapia.