A 12-week feeding trial was conducted to quantify the dietary lysine requirement of juvenile silver pompano with an initial average weight of 6.28 g reared in indoor recirculatory system. Six treatment diets were designed with isonitrogenous, isolipidic and isoenergetic diets. (42% CP, 6% CL and 4.28 kcal g −1 GE) were formulated with graded levels of lysine (1.52, 1.85, 2.21, 2.49, 2.74 and 2.98 g/100 g, dry diet). Equal amino acid nitrogen was maintained by replacing lysine with nonessential amino acid mixture. Fish were randomly stocked, in triplicate groups, in 180 L indoor glass rectangular tanks with recirculatory system and fed to apparent satiation over two feedings at 10:00 and 16:00 h daily during the experimental period. The results indicated that there were significant differences in growth and feed utilization among the treatments. Fish fed diets with lysine in different treatments showed high survival rate (95-100%). Maximum weight gain (WG), specific growth rate (SGR) and protein efficiency ratio (PER) occurred at 2.21% dietary lysine. The hepatosomatic index (HSI), viscerosomatic index (VSI) and crude protein content in whole body were significantly affected by dietary lysine levels. There were significant differences (P < .05) in total serum protein levels and erythrocyte count in fish fed diets with different dietary lysine levels. No significant differences were observed in the levels of serum glucose, triglycerides and creatinine levels among the treatments. In the present study, optimization of fitted quadratic regression of weight gain%, SGR, PER and FER on lysine in diet revealed that the optimum lysine requirement of silver pompano was in the range of 2.40-2.45% of dry diet (5.71-5.83% of dietary crude protein).

Feed represents the single largest input in commercial aquaculture comprising about 60% of the total operating cost (De Silva & Anderson, 1995). The present requirement of aquafeed is estimated to be 60 million tonnes (FAO, 2014). Presently, both protein and energy rich conventional dietary ingredients are of short supply which necessitates incorporating unexplored unconventional locally available ingredients in aquafeed. Oil cakes are conventional protein sources used for carp culture in Asia along with deoiled rice bran (DORB), which is predominantly used in aquafeeds (Meshram, Deo, Kumar, Aklakur, & Sahu, 2018). DORB is an agricultural by-product, which is the most common ingredient used with oil cake. This is a cheap source in aquafeed, which is available throughout the year (Veerina, Nandeesha, & Gopal Rao, 1993).In the recent past, it is observed that the price and utilization of

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Background: The current study was conducted to prepare an efficient super-paramagnetic iron oxide nanoparticle (SPIONs) to remove Aeromonas hydrophila from water. Methods: The nanoparticles were synthesized by the co-precipitation method and characterized by DLS, UV-Vis spectrophotometer, FT-IR, XRD, FEG-TEM, and VSM analysis. Results and Discussion: The results showed that the synthesized SPIONs were having a size range of 8-12nm with magnetic property. Bacteria removal efficiency and antibacterial activity of SPIONs were assessed in sterile distilled water by adding different concentrations of SPIONs viz. 0, 6.25, 12.5, 25, 50, 100, 200, 500, and 1000µM with different initial bacterial loads viz. 1×103, 1×104, 1×105, 1×106, and 1×107 CFU mL−1 at different time intervals 15, 30, 45, and 60 min. At low bacterial load (1×103 to 1×105 CFU mL−1), 95 to 99.99% of bacteria were removed by low SPIONs concentration (6.25-100µM) by 15min which was increased up to 100% by 30min. However, at high bacterial load (1×106 to 1×107 CFU mL−1), more than 87 to 95% of bacteria were removed by the highest SPIONs concentration (1000µM) by 15min, which was increased above 93 to 99.99% by increasing the exposure time to 60min. At low bacterial load (1×103 to1×105 CFU mL−1), the effective concentration was 3.21 to 6.42µM at 15-60 min intervals. Meanwhile, the effective concentration at high bacterial load was 267.81 µM at 15min, which was decreased to 104.09 µM with increasing exposure time to 60min. Conclusion: Based on the results, it is concluded that the antibacterial effect against A. hydrophila depends on the concentration as well as the exposure time of SPIONs. A low concentration of SPIONs is sufficient to remove 100% of bacterial load in lower exposure time and increasing concentration of SPIONs increases the antibacterial effect. However, further research requires to find the safe concentration of SPIONs for using it as a novel antibacterial agent for the treatment of aeromonads disease in aquaculture.