To evaluate the nutritional quality of the shrimp by-products four approximately isonitrogenous (32 ± 2% crude protein) diets containing different types of shrimp waste meal were fed to duplicate groups of ten fry with an initial mean weight 1.43 ± 0.22g /fish for forty two (42) days. Fishes fed with diet D had the highest mean weight gain (MWG) and specific growth rate (SGR) and those fed with the control diet A had the lowest MWG and SGR. ISSN 2157-6076 2013 www.macrothink.org/jbls 330 There were no noticeable change in food conversion ratio (FCR) of the fishes fed with diets B, C and D which are significantly different from the FCR of those that fed with control diet A. The survival of fry tilapia ranged from 70 to 100%, being 70% for D, 80% for B, 90% for C and 100% for A. There were no significant differences in body protein content among the fish fed with diets B, C, D and the initial fish. The lowest body protein was obtained in the fish fed with control diet. The tilapia fed with control diet had the highest body lipid content as compared to the initial fish. However, there were no significant differences in body lipid content among the fish fed test diets B, C and D as compared to the initial fish. The variations in body ash content of initial fish and those fed with test diets were significantly different. The initial fish had the highest body ash content. Journal of Biology and Life Science

The study evaluated the growth performance, survival and body composition of Oreochromis niloticus fed isonitrogenous (25%) and isocaloric (186 cal/kg) diets containing different types of oils (fish oil (FO) and vegetable oils (VO) (Soybean oil (SO) and Peanut oil (PO)) at 6% level for a period of 42 days. Significant difference was observed in the body weight gain (WG), specific growth rate (SGR), feed conversion ratio (FCR) values, body protein and lipid content.The diet E containing a mixture of vegetable oils in equal proportions (1:1) produced the best results WG (413.25%), SGR (3.86) and FCR (1.37), whereas the diet B (75% FO + 25% VO) showed the poorest performance WG, FCR and SGR. The survival rate ranged from 55 to 100%, being 55% for C (50% FO+ 50%VO), 65% for A (100% FO) and 100% for B (75% FO+ 25%VO), D (25% FO+ 75%VO) and E (100%VO). The type of dietary lipid significantly affected the body composition of fish. Fish fed on diets B (75% FO+ 25%VO), C (50% FO+ 50%VO), E (100%VO) presented the highest body protein content compared to initial fish. The highest body protein content was obtained in the fish fed on diet B (75% FO+ 25%VO). There was no significant difference in the body protein content of fish fed on diet C (50% FO+ 50%VO) and E (100%VO) also between the initial fish and those fed on diet D (25% FO + 75% VO). The lowest body protein content was obtained with fish fed diet with A (100% FO). Tilapia fed diet containing 100% FO, had the highest body lipid content compared to the initial fish. The lowest body lipid contain was observed in the fish fed on B (75% FO+ 25%VO). There was no significant difference in body lipid and protein content among fish fed diet with D (25% FO+ 75%VO) and initial fish. Results of the present study suggest that diet supplemented with a mixture of vegetable oils (SO and PO) could totally replace fish oil and produce the best growth response in Oreochromis niloticus.

Fry monosex Nile tilapia (Oreochromis niloticus) were fed in five dietary protein levels (21%, 25%, 32% 37% and 45%) to investigate casual effects on growth performance, carcass composition and survival rate. Tests were carried out in 10 glass tank (50 x 25 x 40 cm) containers (50 L) of reticulating system maintained at 30 ± 1°C. At the beginning of tests, one hundred tilapia fry were randomly divided into five different groups with two replicates. Diets were fed to duplicate groups of ten fry with an initial weight of 1.25 ± 0.25 g/fish during 42 days. The results showed significant effects of dietary protein on growth performance of reared fish. Weight gain (WG) and Specific Growth Rate (SGR) increased significantly with increasing dietary protein levels between 32.38% and 37.63%. However, 45.5% of crude protein showed less important increase in growth parameters. The best Feed Conversion Rate FCR (1.26) was noticed in diet containing 37.63% of crude protein. Accordingly, higher survival rate (%) was recorded in fish fed on diets containing 32.38 and 37.63%. There was no significant difference in protein body content of tilapia fed on five diets as compared to the initial fish. Lipid body content increased significantly with high dietary protein levels from 21.88% to 45.50%. The carcass crude lipid was recorded as higher (9.4%) in the fry fed on diet containing 45.50% protein, followed by fish fed on diet having protein 21.88%. From results, diet containing 37.63% crude protein appears to be more suitable for monosex Nile tilapia growth, in related experience conditions. In this line, it is recommended to feed monosex tilapia fry.

The effect of substituting fishmeal with crustacean (Callianassa) meal in the diets of mixed sex Nile tilapia (Oreochromis niloticus) fry (0.2 g) was evaluated. Three isonitrogenous and isolipidic diets were formulated to contain 30% CP and 15% CL where fishmeal was substituted with Callianassa meal at 0, 25 and 50% in diets R1, R2 and R3 respectively. The experiment lasted for 6 weeks. The stocking density was 10 fish per tank in an isolated system and the capacity of each tank was 50L. Each treatment was administered in duplicates and fish were fed three times per day (09h, 13h, and 17h). The daily ration corresponds to 10% of the live weight of the fish during the first 2 weeks and was reduced to 8% and then 6% for the second and last two weeks of the trial period. At the end of the experiment, fish fed on R1 (control) diet and R2 diet (25% fishmeal replacement) had similar final weight (0.62 g), absolute mean weight gain (0.42 g), relative mean weight gain (210 %) and specific growth rate (2.50 %) and were significantly different from the values obtained from those fed on R3 diet (50% fishmeal replacement). R3 diet had the best FCR (1.42) and was significantly different from the values obtained from R1 and R2 diets but the values of the diets were not significantly different. The dry matter content of the initial fish (96.33%) and those of the R1 (94.12%) and R2 (95.71%) diets did not differ significantly but were slightly higher than that of the value obtained from fish fed on R3 diet (91.15). The protein content of the initial fish (49.63%) was significantly lower than the values obtained from fish fed on R3 diet (61.95%), R1 diet (54.74%) and R2 diet (52.59%). The fat content of the initial fish (41.51%) was higher than the values obtained when fish were fed on the experimental diets. Among the tested diets, the higher the crustacean meal in the diet, the lower the fat content of the fish muscle. The fat content of R1 (control) diet (29.56%) was slightly higher than the value of R3 diet (24.44%) and slightly lower than R2 diet (32.56%). It is concluded that crustacean meal can replace 25% of fishmeal in the diet of Nile tilapia (Oreochromis niloticus) fry at 0.2 g without any effect on the growth performances and feed efficiency.

The effect of three African medicinal herbs used as feed additive on the growth and survival of Nile tilapia (Oreochromis niloticus) was studied. Four isoproteins (32%) and isolipid (13%) diets, namely RC (control diet or 0% plant), 3% B. vulgaris, 3% K. africana and 3% R. heudelotti, were manufactured. One hundred and eighty (180) Nile tilapia fry with an initial average weight of 0.15 ± 0.01 g were randomly distributed in 12 plastic tanks (50 L / tank) at a density of 15 fish per tank and fed three times (8.00 h am, 1.00 h pm and 5.00 h pm) per day for 90 days. For the parameters studied (average weight gain (AWG), feed conversion ratio (FCR), specific growth rate (SGR) and survival rate (SR)) no significant difference was observed between diets at the end of the experiment. Furthermore, the addition of 3% K. africana or B. vulgaris or R. heudelotti had no impact on the dry matter, ash, crude protein and whole-body fat content of Nile tilapia fry. This study showed that 3% B. vulgaris or K. africana or R. heudelotti has no adverse effect on the growth, survival and whole-body composition of Nile tilapia fry.

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This experiment was carried out in order to know the variation of the morphometric relation between the length and the width of the shell of abalone Haliotis tuberculata as well as the evolution of the factor of condition.Haliotis tuberculata used in the study is a gastropod that belongs to the order Vetigastropoda, and the family Haliotidae. 135 abalones with an average weight of 5.55±1.24 g, an average length and shell width of 3.14±0.23 cm and 2.12±0.18 cm were selected for the experiment.These individuals were divided into three different densities (10, 15, 20 individuals) in nine (9) plastic tanks with a base area of 0.15 m2 of 3 tanks per density. The abalones from each tank were fed 70% of their body weight with available macroalgae such as Ulva lactuca and Dictiopeterus sp. Morphometric relationships that include the relationships between length-width and condition factor were determinedAt the end of 12 months of experimentation, changes in length, width, and annual average weight as a function of density indicate that low stocking densities favor a faster increase in these variables (length, width, and weight). The analysis of these relationships indicates a strong correlation between the length and width of the Haliotis tuberculata shell. However, it is noted the correlation between these two variables decreases inversely with density. The average values of the condition factor are 18.89 ± 0.96, 18.72 ± 1.18 and 18.59 ± 1.14 for densities D10, D15 and D20 respectively. Analysis of the results of this study shows that when population density becomes too high, the growth of H. tuberculata is slowed down both in weight and in size. The condition factor analysis also indicates that the best biological performance is obtained at the lowest density (D10) thus inducing better growth.

This study aimed to evaluate the impact of plant-based food additives on growth performance, body composition and survival of Nile tilapia. Four isonitrogenous (25% CP) and isolipidic (13% CL) experimental diets were prepared and designated as R1, R2, R3, and R4. R1 contains (3% Cymbopogon citratus), R2 contains (3% Ocimum basilicum), R3 contains (3% Mentha spicata) and R4 (control or 0% additive). 180 Nile tilapia fry with an initial average weight of 0.2g were distributed in 12 plastic tanks (50 L/tank) at the stocking density of 15 fish per tank in an isolated system. Fish were fed with experimental diets 3 times per day (8:00 am, 1:00 pm and 5 :00 pm) for 3 months. After 90 days of experiment, the results revealed that the final average weight ranged from 2.62g to 8.00g, the absolute average weight gain (AAWG) from 2.42 to 7.8g, the feed conversion ratio (FCR) from 1.31 to 2.67 and specific growth rate (SGR) from 3.06 to 4.36%/d. The survival rate (SR) varied between 64 and 100%. Of the parameters studied such as the absolute average weight gain (AAWG), the specific growth rate (SGR), the feed conversion ratio (FCR), and the survival rate, the best were obtained by the group of fish fed with the R2 diet containing 3% Ocimum basilicum. The results of the analysis of the flesh showed that the addition of 3% O. basilicum does not modify the contents of dry matter, crude protein, and ash but slightly increased the fat content. Based on the results, the inclusion of natural plant-based food additive (3% Ocimum basilicum) in the diet of Nile tilapia improved the parameters of growth, feed efficiency, and survival.