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This study was conducted to determine the effects of dietary methionine and lysine supplementation on digestive enzymes activity in juvenile Sobaity, Sparidentex hasta. For this purpose, 180 juvenile fish with an initial average weight of 31.38 ± 1.4 g were distributed randomly in eighteen (300 L) polyethylene tanks. 6 experimental diets were prepared with different levels of methionine and lysine including control diet (without dietary methionine and lysine), Diet 1: 100% methionine; Diet 2: 75% methionine and 25% lysine; Diet 3: 50% methionine and 50% lysine; Diet 4: 25% methionine and 75% lysine; Diet 5: 100% lysine. During the experimental period, fish were fed to satiation thrice daily (8:00, 13:00 and 18:00 hours) for 8 weeks. At the end of the experiment, digestive enzymes (trypsin, chymotrypsin, alkaline phosphatase, amylase, lipase and total protease were effected by different dietary levels of methionine and lysine supplementations (P<0/05). Also, the activity of trypsin and chymotrypsin had showed an increasing trend with increased amount of diet lysine while enzyme activity of alkaline phosphatase was higher in treatments contains maximum amount of methionine supplementation. According to results, the increasing of lysine in diet reduced enzyme activity of lipase. The results, showed no significant differences between experimental treatments in amylase and total protease (P<0/05). Based on the results of evaluation digestive enzymes, amino acids supplements of lysine and methionine were changed the activity of digestive enzymes in juvenile Sobaity, (S. hasta). Finally, Diet 2 with 75% methionine and 25% lysine was suggested for used by Sobaity, as to the balance of dietary methionine and lysine supplementation.

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In this study that lasted to 8 weeks, was conducted to determine  the effects of dietary supplementation of lysine and  methionine on body biochemical composition and amino acid profile of Sobaity sea bream, Sparidentex hasta. Therefore, 180 juvenile fish with an initial weight of 31.38 ±1.4 g were distributed randomly among eighteen tanks. Fish were fed to satiation three time per day (08:00, 13:00 and 18:00 hours) with formulated diets containing six different levels of dietary methionine and lysine; Diet 1: a control diet without dietary amino acid supplementation; Diet 2: 100% methionine supplementation; Diet 3: 75% methionine and 25% lysine supplementation; Diet 4: 50% methionine and 50% lysine supplementation; Diet 5: 25% methionine and 75% lysine supplementation and Diet 6: 100% lysine supplementation.The results of this study showed Carcass protein content was significantly affected by the amino acid supplements and the highest level of carcass protein observed in fish were fed by diet 3(P<0.05). Also Increasing levels of  lysine in diet caused increases the amount of fat in the carcass although the content of carcass fat, moister and ash were not significantly different among thetreatments (P > 0.05). In addition, essential amino acids (ΣEAA) and non-essential amino acids (ΣNEAA) and  ratio ΣEAA / ΣNEAA, were affected by lysine and methionine amino acid supplementation as ΣEAA and ratio (ΣEAA) / (ΣNEAA) significantly increased with increasing levels of amino acid supplementation and the highest amount of this parameters observed in groups were fed by diet with high levels of methionine.The results showed that adding 75%  dietary methionine supplementation and 25% lysine supplemtation to the diet containg 45/95% protein, have positive effects on biochemical composition and amino acid profile in rearing of Sobaity seabream juveniles.

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On this study effects of reducing arginine, phenylalanine and tryptophan amino acids in diets of Sobaity seabream in a constant level (40%) on growth, nutritional indices, whole body chemical proximate and amino acids, was assessed. For these purposes four different treatments in triplicate was used during 42 days in base of feeding with semipurified diets containing crystalline amino acids. The control diet was without any deficiency, the arginine (ARG), phenylalanine (PHE) and tryptophan (TRP) diets were deficient in arginine, phenylalanine and tryptophan respectively. Crystalline amino acids were used to formulate diets precisely with desired amounts of deficiency. In fish fed ARG diet, just two factors including nitrogen retention and percentage of weight gain decreased in comparing with control group (P > 0.05). But in PHE and TRP treatments all the growth and nutrition factors including final weight, weight gain, specific growth rate, feed consumption, protein efficiency and nitrogen retention decreased significantly regarding to the control group (P > 0.05). The experimental treatments affect whole body proximate regarding to the control by increasing whole body moisture in PHE, reduction of gross energy in all treatments and reduction of Crude lipids in TRP and PHE (P > 0.05). Reduction of whole body protein in ARG treatment showed using more protein rather than lipids as a source of energy in this group of fish. Reduction of whole body lipid in all treatments regarding to the control group showed some disorder in lipid metabolism. In spite of arginine, phenylalanine and tryptophan deficiency in diets, the amounts of these amino acids in fish whole body did not decreased that showed amino acids sparing effect for these three essential amino acids happened in fish body. The results of the current study showed that reduction of one single essential amino acid from diet have strong effects on other amino acids retention and consequently reduces protein synthesis and growth.

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Pheromones are molecular signals of hormones or their derivatives that affect the same species in the environment outside the body. The effect of ovary extract of psyllium as a pheromone-containing substance (PGF2α) on pheromone induction and the process of final sexual maturation and changes in male sperm indices of this fish have been investigated and compared in different treatments. Male fish with an average weight of 45 ± 200 g were released in 300 liter fiberglass ponds and after adapting the fish to the environment (for 48 hours), the experiments were performed in 5 experimental groups (one control group, one prostate gland control group and 3 groups Treatment) in which each group consisted of 9 adult male fish. Different concentrations of ovarian extract were added to the water in three treatments of 5, 10 and 15 mg / l as a bath. After 24 hours, the fish were anesthetized and fish biometrics was performed by measuring length and weight. After blood sampling, fish gonads were weighed. The results showed that pheromone induction of ovarian extracts and their positive effect on increasing the rate of sperm counts. Gonadosomatic index as well as testosterone levels at 10 and 15 mg / l treatment and prostaglandin treatment (PGF2α) were significantly increased compared to the control (p <0.001). Sperm density and spermatocrit in the treatment of 15 mg / l (T3) had a significant decrease compared to the control, but the indices of sperm motility rate and sperm motility percentage compared to the control did not show a significant difference. Relative sperm volume in all treatments was affected by pheromone extract and a significant increase was observed compared to the control in T3 treatment (p <0.001). Administration of pheromone extract resulted in control of male reproductive fish reproduction in all experimental groups.