This study was aimed to investigate the effects of two probiotics, Bacillus cereus and Pediococcus acidilactici, on the water quality, growth performance, the survival ratio, economic benefits, immunohematology and bacterial flora in the intestine of whiteleg shrimp, Litopenaeus vannamei after 110 days. Nine earthen ponds (each one 1.2 hectare) were adjusted as three treatments including control (without adding bacteria), containing P. acidilactici probiotic (106 CFU/mL) and containing B. cereus probiotic (106 CFU/mL). The results showed that the adding B. cereus and P. acidilactici to the water pond positively decreased nitrate, ammonia and biochemical oxygen demand when compared with the control group (p < .05). Regarding growth performance, treating shrimp with B. cereus caused significantly higher weight gain (16.72 g) and survival ratio (94.50%) in comparison with control group (p < .05). Using these probiotics could increase shrimp production (27.30%, 18.42%) and net income (92.94%, 49.20%) as well. Respect to immunity, total hemocyte count (9.00), total protein (8.92 g/dl) and lysozyme activity (21.55 U/ml) in treated whiteleg shrimp with B. cereus were significantly higher than those untreated (p < .05). In conclusion, adding B. cereus (106 CFU/ml) to the earthen pond can be suggested in shrimp farm.

A three-month research was conducted to evaluate the influence of supplementing a plant protein- (PP-) rich diet (60% of fish meal (FM) was replaced with a mixture of alternative PP sources) with selenium nanoparticles (Se-N) on sperm kinetics, fertilization capacity, and antioxidative responses in Arabian yellowfin sea bream (Acanthopagrus arabicus) males. In this point, graded levels of Se-N at 0, 0.5, 1, 2, and 4 mg/kg were added to the PP-rich diet. Also, a FM-based diet was used as a positive control. Two hundred and eighty-eight brooders (males: 195.3 ± 10.8  g and females: 237.5 ± 8.1  g; mean ± standard   error ) were randomly distributed into eighteen 10 m3 rectangular concrete tanks (8 males: 8 females in each tank), and every three tanks were fed with one of the experimental feeds for three months. The seawater temperature and salinity were 18-22°C and 40-41‰, respectively, during the husbandry period. Selenium retention increased in the liver, testes, and semen of males with increasing dietary Se-N level ( P < 0.05 ). Sperm density in fish fed with 2 mg Se-N/kg PP-rich diet ( 42.1 × 10 9 / mL ) was higher than those fed control, 0, 0.5, and 1 mg Se-N/kg PP-rich diets. The percentages of sperm motility in 60 s and 300 s after activation, sperms with straight movement, the longevity of sperm motility, and fertilization rate increased with increasing Se-N level in the PP-rich diets ( P < 0.05 ). The highest and lowest semen superoxide dismutase activities were in fish fed 4 and 2 mg Se-N/kg PP-rich diets, respectively. The highest glutathione peroxidase activity in semen was in fish fed 4 mg Se-N/kg PP-rich diet, and the lowest values were in fish fed 0 and 0.5 mg Se-N/kg PP-rich diets. Total antioxidant capacity values in semen of fish fed 1 and 4 mg Se-N/kg PP-rich diets were higher than the other treatments. Fish fed with PP-rich diet without any Se-N supplementation had higher malondialdehyde level in the semen compared to the other groups. Results showed that supplementing PP-rich diet with 2-4 mg Se-N/kg can improve sperm kinetics and enhance fertility potential in A. arabicus males.