In this study, the effect of spirulina meal (Spirulina platensis) as a feed additive on growth and physiological response of Oscar fish,Astronotus ocellatus, was assessed using four diets including control without spirulina supplementation, 13.75 g/kg spirulina (SP1), 27.50 g/kg spirulina (SP2) and 55 g/kg spirulina (SP3). One hundred and twenty fish (10.41 ± 0.25 g) were disturbed to twelve aquariums and fed to apparent satiation three times a day for 8 weeks. The result showed that the SP3 treatment had statistically better growth performance, feeding parameters, total protease activity, total protein and lipid contents than the control. Moreover, haemoglobin, haematocrit, mean erythrocyte haemoglobin and mean erythrocyte haemoglobin concentrations were improved considerably in the SP3 treatment compared with the control. The SP3 treatment showed higher total protein and albumin levels, but lower triglycerides, cholesterol levels and liver enzyme activities than the control. Also, serum complements (C3, C4), lysozyme activity and total carotenoid contents in fish skin significantly increased in the SP3 treatment compared with the control. The results of this study suggest that spirulina powder at the level of 55 g/kg of the diet can be used as a functional natural feed additive to improve the performance of Oscar fish.

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In recent decades, interest in using medical plants powders as growth factors and immunestimulants in aquaculture has been increased. This study was conducted to evaluate the effect of different levels of dietary supplementation of garlic, Allium sativum on growth factors and body composition of Molly Fish, Poecilia sphenops. Four diets containing supplementation at levels of 0, 5, 15 and 30 g kg −1 were fed to fingerlings of Molly Fish (initial weight, 0.85 g) in triplicates tanks three daily to apparent satiation for 56 days. The result of experiment showed, growth performance and feed efficiency were improved in all treatments compared with control group. But according to the results, the best final weight, weight gain rate (WGR%), specific growth rate (SGR) and food conservation ratio (FCR) were observed in the fish fed 15 g kg -1 A.sativum in diet. The highest protein content was obtained in the fish fed with dietary with 15 g kg −1 A.sativum powder. Also fat tissue of fish had significantly decreasing trend compared with control group. Moisture and ash contents were no significantly affected by A.sativum. The results of the present study indicated clearly that the supplementation of A.sativum (15 g kg −1 diet) enhanced the growth performance, feed utilization and body composition of Molly Fish, P.sphenops.

The aim of this study was to investigate the synbiotic effects of Pediococcus acidilactici (PA) and isomaltooligosaccharide (IMO) on the performance of juvenile common carp (Cyprinus carpio). A total of 360 fish ( 17.22 ± 0.19  g) were randomly divided into six groups with three replicates of 20 fish each. The trial continued for 8 weeks. The control group was fed only basal diet; PA was fed basal diet supplemented with 1 g/kg (1010 CFU/kg) PA, IMO5 (5 g/kg IMO), IMO10 (10 g/kg IMO), PA-IMO5 (1 g/kg PA and 5 g/kg IMO), and PA-IMO10 (1 g/kg PA and 10 g/kg IMO). The results indicated that the diet containing 1 g/kg PA and 5 g/kg IMO significantly increased the fish growth performance and decreased the feed conversion ratio ( p < 0.05 ). Overall, blood biochemical parameters, serum (lysozyme, complements C3 and C4) and mucosal (protein, total immunoglobulin, and lysozyme) immune responses, and antioxidant defense of fish also improved in the PA-IMO5 group ( p < 0.05 ). Therefore, a combination of 1 g/kg (1010 CFU/kg) PA and 5 g/kg IMO can be recommended as a beneficial synbiotic additive and immunostimulant in juvenile common carp.