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Effects of feeding Artemianauplii enriched with PHB (0, 0.1, 0.3 and 1 g/L concentration) on the growth performance, body composition, digestive enzyme activity and hindgut bacterial community in the Persian sturgeon hatchlings were investigated. PHB treatment significantly (p≤ 0.05) decreased growth performances of the hatchlings. The PHB also significantly increased the total saturated fatty acids (SFA) and n6, but decreased the total MUFAs, C18:3n3, n3 and n3/n6.  PHB also altered digestive enzyme by significantly decreasing  the total protease, amylase, and lipase. Based on molecular analysis, PHB changed the microbial community in the hindgut of the hatchlings where less dominant bands were observed. Our results show that PHB has negative effects on the Persian sturgeon hatchlings.  Further studies are needed to find out the optimal concentration of PHB to apply in early larval rearing of sturgeon.

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Aims: Biofloc system is the usage of microorganisms such as heterotrophic bacteria, algae, dietary zooplanktons, and protists, which disintegrates and consumes reared aquatics propagation and non-eaten foods in ponds and increases the productivity of developed ponds as a modern aquaculture system. The aim of this study was to investigate the quality of common carp meat reared in the biofloc system during the refrigerated storage time (4±1°C).
Materials & Methods: In this experimental study, 300 common carps were fed for 9 weeks by commercial food (control) and 3 experimental treatments were fed, and the quality indices of meat were evaluated. The data were analyzed by SPSS software 21, using Duncan's multiple range, one way ANOVA, and Tukey post hoc tests.
Findings: The lowest meat taste quality was observed in sugar beet molasses treatment and it had a significant difference with other treatments (p<0.05). No significant difference was observed in case of sensorial parameters and cooking loss percentage in fish meat (p>0.05). Control and sugar beet molasses treatments showed the lowest and highest skin redness index values, respectively. Thiobarbituric acid (TCA) value significantly increased and decreased in control and biofloc treatments, respectively, over storage time (p<0.05). Sulfhydryl and TCA soluble peptides values decreased during refrigerated storage time (p<0.05).
Conclusion: The biofluid system has a positive effect on the quality of common carp meat reared during the refrigerated storage time and increases its shelf-life.