Sex control in tilapia should provide an invaluable benefit to aquaculture. The effects of different dietary levels of papaya carica seed meal powder on growth and gonad histology in Oreochromis niloticus larvae were studied to prevent early maturity and uncontrolled spawning. Four (4) dietary level of seed meal powder, varying from 0 g.Kg-1 as a control; 1 g.Kg-1 ; 2 g.Kg-1 to 3 g.Kg-1 were each tested in triplicate. The diet were isonitrogenous and were fed to twelve (12) experimental groups of 110 larvae weighing 0.019 g at a feeding rate of 4% body weight, three times a day for 30 days with the experimental diet and then after fed with the basal diet for other 60 days of the experiment. At the end of the experiment, 24 fish from all replicates were randomly sampled, slaughtered and dissected to remove testicles and ovaries. Testicular and ovarian sampleswere fixed in 10% buffered formalin for 24 h before the histological process. After 90 days of experiment, fish weight increased from 0.019 g ± 0.09 to 32.47g ± 0.02; 30.40g ± 0.05; 34.68 g ± 0.07 and 33.83 g ± 0.09 respectively for C. papaya dosage of 0; 1; 2 and 3, respectively. In fish treated with 0 and 1 g.Kg-1 of PSM, the testes showed different stages of spermatogenesis with germ cells moving up to the spermatozoa. Similarly, the ovaries showed follicles at different stages of folliculogenesis up to vitellogenesis. The main lesional changes observed concerned the testicles of fish fed with 2 and 3 g.Kg-1 PSM with in particular the scarcity of germ cells and spermatozoa. For females, the only observations concern vitellogenesis which are important for treatment doses of 0 and 1 g.Kg-1 , while they decrease in the group treated with 3 g.Kg-1 .

Objective: This feeding trial was designed to assess the effects of formi (Dietary potassium diformate) supplementation in shrimp diet on growth and survival of white shrimp, Litopenaeus vannamei. Methodology and results: Seven isonitrogenous diets were formulated with graded formi levels of 0, 1, 2, 4, 8, 14 and 20 mg kg-1 of dry diet, respectively. Shrimps were randomly allocated to twenty four (24) 50 l aquariums (10 shrimps of 0.82 ± 0.08 g per aquarium, eight treatments and three replicates). Water salinity was set at 17 g L-1 and the flow rate of each aquarium maintained at 2 L min-1 and decreased to 1 L min-1 at day 41 th. Shrimps were exposed to 18:6 hours light/dark photoperiod. The results showed that water quality parameters did not vary significantly with the dietary supplementation and was optimal for growth and survival of L. vannamei. The maximum weight gain and survival occurred at 14 mg kg-1 formi diet. However, no significant differences were observed in percent weight gain (WG), specific growth rate (SGR), feed conversion ratio (FCR) between diets with different levels of formi supplementations. The survival rate data varied between 73.33 % and 100 %. Survival rate revealed that the commercial diet had the lowest survival. At the end of the study no significant effects on the growth, survival, feed efficiency and water quality of white shrimp, Litopenaeus vannamei was found.

La présente étude a été menée pour évaluer les effets de l'incorporation de la farine de soja dans le régime alimentaire des juvéniles de la perche du Nil. Ce travail est réalisé sur des juvéniles de 1g élevés dans des aquariums de 50 l. Cinq régimes alimentaires isoprotéiques (45% de protéines) contenant différents taux de farine de soja 0%, 26%, 36%, 51% et 60% noté respectivement A, B, C, D et E ont été préparés. Chaque régime a été assigné de façon aléatoire à trois groupes de poissons nourris à satiété durant 8 semaines. Les résultats obtenus montrent que les meilleures performances de croissance et d'efficacité alimentaire sont obtenues avec les régimes nourris avec la farine de poisson (A), suivis dans l'ordre des régimes B, C, D et E. Les taux de croissance spécifiques (TCS) varient entre 3,26% et 3,77% respectivement chez les poissons nourris avec les régimes A, B, C, D et E. Le coefficient d'efficacité protéique (CEP) a varié de 2,07 à 1,6. Les résultats statistiques montrent que le meilleur CEP est obtenu avec le régime A (P< 0.05) et le plus faible avec le régime E. Les résultats de la présente étude indiquent qu'il est possible d'incorporer 51% de la farine de soja dans l'alimentation des juvéniles de Lates niloticus sans compromettre leur croissance.

Nile perch (Lates niloticus, Linnaeus, 1758), is a carnivorous fresh water fish that have good market demand and suitable for aquaculture. The present study was designed to determine the effect of dietary protein level on growth and body composition of juveniles Nile perch. Five experimental diets with increasing levels of protein (30, 35, 40, 45 and 50 g crude protein 100 g-1 feed) were prepared and fed in duplicate groups of Nile perch (initial weight : 8.67±0.17 g) reared in ten 50 L tank for 8 weeks. Results showed that dietary protein level significantly influenced weight gain, specific growth rate and feed conversion ratio. The WG and SGR increased with increasing the protein level up to 45% content. Feed conversion ratio was lowest in Nile perch fed 45% protein and highest in those fed 30% protein. Fish fed with the 30% protein diet had the lowest survival and those fed 50% protein diet had the highest survival. There was no significant difference (P>0.05) in Moisture among the dietary treatments. Protein and lipid showed linear increase as dietary protein levels increased. Fish fed diet ≥ 45% protein had the highest protein content, followed by fish fed 30 to 40% protein and lowest in the initial fish. Fish fed diet containing 50% protein had the highest lipid carcass content, whereas the lowest lipid content among treatment was observed in the initial fish. Under the experimental conditions applied, juvenile L. niloticus, require 45% dietary protein for optimized growth.

This present study was conducted to determine fry production in different male-female sex ratios of Oreochromis niloticusbroodstock in order to improve fry production, which handicapped the development of fish farming in northern Senegal. A total of 180 broodfish (47 males and 133 females) were stocked at a density of 2 fish /m2and was replicated three times for each sex ratio of 1:2, 1:3and 1:4 (male : female). Mean body weight ranges from 136.47±2.13 and 107.27±2.14 g for female and male O. niloticusbroodstock, respectively. The experiment was conducted for 90 days and the broods were fed on commercial diet containing 32% crude protein.Fish were held in 9 rectangular tanks of 30 m3 each (10 × 3 × 1) and half-filled. The results showed that number of fry produced at different sex ratios were significantly different, with sex ratio of 1:2 producing a highest number of fry (279.67) per female, followed by the 1:3and 1:4 treatment recorded the lowest.Broodstock sex ratios also did not affect female survival rates and all treatments had 100% survival rates. Temperature, dissolved oxygen and pH values obtained were suitable for good water quality and normal tilapia reproduction.In conclusion, the results of the present study recommend to stock Oreochromis niloticus brooders when stocked at a density of 2 fish /m2 at a sex ratio of 1 male : 2 female in order to obtain the highest fry production.