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In the present study, the Amphora coffeaeformis diatom was applied in different concentrations to the diet of Nile tilapia (Oreochromis niloticus) to investigate its potential effects in improving growth performance, as well as enhancing immune and antioxidant responses to control Aeromonas hydrophila infection. The tilapia fingerlings were divided into 4 groups, and for 4 weeks were fed A. coffeaeformis at various concentrations (0, 1, 2 and 3%). Growth‐stimulating activity from dietary A. coffeaeformis was observed, particularly in the 2% and 3% treatment groups. Furthermore, serum immunoglobulin M (IgM), nitric oxide (NO), malondialdehyde (MDA), total‐superoxide dismutase (T‐SOD), catalase (CAT), and glutathione peroxidase (GPx) were evaluated at the 2nd and 4th weeks from the onset of feeding and showed significant improvement (p < 0.05) in the 2 and 3% groups. At the end of the feeding trial, the tilapia were challenged via an intraperitoneal (IP) injection of virulent Aeromonas hydrophila. Fish survival, serum IgM, nitric oxide, MDA, T‐SOD, CAT, GPx, and liver, kidney, spleen, and gill histopathology were all evaluated post challenge. Significant improvements in both immunological and antioxidant parameters continued until the post‐challenge measurements. Overall survival was significantly increased in the 2 and 3% groups, compared to the control and 1% groups. Histopathological examination revealed a decrease in the degenerative and destructive effects of A. hydrophila infection on the liver, kidneys, spleen, and gill tissues, indicating that dietary A. coffeaeformis administered at concentrations of 2 and 3% could be recommended as a feed additive for the control of A. hydrophila infection in Nile tilapia.

A feeding trial was carried out to study the effect of dietary inclusion of different levels of ginger on growth performance, feed, nutrient utilization, body composition and cost benefit analysis of the Nile tilapia. Nine hapa (3×3×1 m 3 ) were used, each was stocked with 50 fish (overage initial weight 10 g/fish). Nine experimental diets were formulated to contain (0.5 and 10% of ginger extract protein instead of soybean meal protein). All the diets were isonitrogenous (30% protein) and isocaloric (4500 Kcal/kg) diet, gross energy. Fish were fed on the experimental diets at a rate of 5% of their body weight daily for 16 weeks. The feed amount was given at two times daily. Nile tilapia fed the diet containing (1%) ginger extract exhibited the best performance, feed conversion, and protein efficiency ratio compared with the control and level 0.5% ginger in fish diets. The body composition was not affected by ginger extract up to 0.5% inclusion level. However, the higher level of ginger inclusion caused high protein and low lipid contents of fish body than the control diet. Cost benefit analysis showed high profil index and low incidence cost with the ginger inclusion in the diets. Saad M. Alsaiad and Ahmed M. Al-Zayat 24This study was undertaken to determine the usefulness of Ginger fed to Nile tilapia fingerlings on its growth and economic performance, body composition and organs indices. MATERIALS AND METHODS Experimental conditions:The present study was conducted to investigate the effects dietary supplementation of Ginger extracts as natural growth promoters on growth performance, nutrients utilization, survival rates, whole body composition and economic efficiency of Nile tilapia (Oreochromis niloticus) fingerlings were reared in cages constructed into earthen ponds system. The study was conducted in the fish farm belonging to General Authority of Fish Resources Development (GAFRD) located at El-Hamul city (El-Zawya fish farms), Kafr El-Sheikh Governorate, Egypt.The main water source of the farm is the drainage canal called Hamdy canal, during the rearing period (16 weeks, 112 days) from 29 th June to 18 th October 2014 16 weeks (112 days). Experimental design:The feeding trial was conducted in three groups of healthy monosex fingerlings Nile tilapia (O. niloticus) fish in nine m 3 (3 x 3 x1 m) net cages (in triplicate) each contained 432 fish by rate (5.5fish/ m3) were placed into one earthen pond system with a total area each of 525 m2 (15 x 35 m.), with a depth of 1.5 m and water flow.Triplicate per treatment were used in this study as following: Group 1 (T1) control: considered as control diets (basal diet without Ginger extracts). Group 2 (T2): 0.5 % Ginger extracts. Group 3 (T3): 1.0 % Ginger extracts.Net cages were set on wooden stales and attached to wooden structures. The pond was rectangular in shape, well exposed to sunlight, independent completely free from aquatic vegetation, basin conformation and bottom soil type were also similar. The pond has inlet and outlet facilities. The main source of w...