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Replacement of olive pomace (OP) with wheat flour in diet was studied in diet of yearling Siberian sturgeon (Acipenser baerii). Fish (165 ± 6.8 g) were randomly allocated to 15 fibreglass tanks (15 fish/tank, in triplicate). Fish were assigned to one of five dietary treatments at 19.1 ± 1.5°C for 8 weeks: control diet (crude protein and crude lipid at 514.6 and 188 g/kg, respectively) and four experimental diets with 20, 50, 75 and 100 g/kg OP to replace wheat flour in the experimental diets. No significant difference was observed in the final weight, feed conversion ratio, specific growth rate, hepatosomatic index, viscera‐somatic index and survival rate among the treatments (p > 0.05). No change was seen in digestibility of protein and lipid in diets containing 20 g/kg and 50 g/kg OP compared to control group, while these values decreased with increasing in OP above 50 g/kg. Digestibility of dry matter and gross energy among the treatments demonstrated no significant difference (p > 0.05). Polyunsaturated fatty acids, especially C22:6n3 (DHA), in the muscle of the fish fed 75 g/kg and 100 g/kg OP in diets were significantly higher than control group (p < 0.05). These data show that OP could be recommended as a substitute for wheat flour in diet of S. sturgeon but its utilization for other species warranted future works. [ABSTRACT FROM AUTHOR]

The objective of this study was to assess the effects of rearing density on the growth and fatty acid profile of Nereis diversicolor and on its capability to bioremediate wastewater in an integrated culture system with rainbow trout (Oncorhynchus mykiss). To this end, a batch of juvenile N. diversicolor (0.03 ± 0.01 mg) was assigned into four different densities (T1 = 250, T2 = 500, T3 = 1,000, T4 = 2,000, besides T0 = with no worm) in three replicates. The worm groups were fed with solid waste that was supplied from tanks containing rainbow trout (107.17 ± 13.5 g; 1.39 ± 0.18 kg/m3). During the experiment (60 days), the water temperature was 17.71 ± 0.6°C. The results revealed that SR%, SGR% and WG% of N. diversicolor in T1 were significantly higher than those of T2, T3 and T4. Both FER rate and biomass gain in T4 were significantly higher than those in the other groups. The highest removal rate of NO2‐N (73.72%), NH3‐N (65.70%), PO4‐P (59.32%), BOD5 (69.60%) and TSS (82.33%) were observed in T4. The major fatty acids presents were palmitic acid, oleic acid, linoleic acid, stearic acid and alpha‐linolenic acid in all worm‐treated groups, with no difference observed in the concentration of these fatty acids among them. Taken together, these findings suggest that organic wastes from rainbow trout farms could be recycled to achieve a sustainable aquaculture goal, and demonstrate that a high percentage of fatty acids in fish feed is not absorbed by rainbow trout but is done by N. diversicolor. [ABSTRACT FROM AUTHOR]

This study was undertaken to evaluate the role of polychaete Nereis diversicolor in bioremediation of waste water and its growth performance and fatty acid composition in an integrated culture system with great sturgeon, Huso huso. Three treatments consisting of N. diversicolor fed with H. huso waste ( FNW), N. diversicolor fed with fish feed waste ( NW), and fish waste without the worm ( FW) were considered at water temperature of 23°C for 8 weeks. The obtained results demonstrated that N. diversicolor in the flow-through system could grow via feeding with the fish waste water. The pure production and survival rate of harvested Nereis in NW treatment were significantly higher than those of FNW treatment ( p < .05). However, no significant difference was observed in specific growth rate and weight gain between these two treatments ( p > .05). The highest removal efficiency of waste water including total nitrogen (56%), total phosphorus (53%), NO2-N (91%), NH3-N (35%), PO4-P (47%), BOD5 (60%) were seen in FNW treatment. Also, the highest additional efficiency of NO3-N occurred in FW (37%) treatment. Certain fatty acids specifically 20:5 ω3 (eicosapentaenoic acid [ EPA]) and 22:6 ω6 (docosahexaenoic acid [ DHA]) were also abundant in Nereis, and analysis revealed some differences due to the diet. These results demonstrated that the promotion of growth by cultured Nereis can enhance the decomposition rate of organic matter in enriched sediment and minimize negative effects in fish farms. These results also suggest that the use of N. diversicolor is an excellent potential candidate for an integrated aquaculture and nutrient recycling including the removal of organic wastes. [ABSTRACT FROM AUTHOR]

Physico-mechanical and antioxidant properties of glycerol plasticized fish gelatin films were investigated at different levels of fish protein hydrolysates (FPH) from silver carp muscle (5, 10, 15, and 20 g FPH/100 g gelatin). The films supplemented with FPH, especially at higher concentration showed significant increase in 2, 2-diphenyl-1-picrylhydrazyl (DPPH), 2, 20-azinobis-(3-ethylbenzothiazoline-6-sulfnic acid) (ABTS) radical scavenging, and ferric reducing antioxidant power (FRAP), elongation at break, difference of color, water vapor permeability and opacity, while tensile strength, elastic modulus, L , b , and contact angle decreased markedly (p < 0.05). However, no significant differences were observed for a and solubility of all samples (p > 0.05). Films prepared using 20% FPH had lower glass transition temperature and more homogeneous structure, compared with control film. Also, Fourier transform infrared (FTIR) spectroscopy confirmed the increase of free groups of hydrolysates and lower interaction between chains of film incorporated with the highest content of FPH. Thus, these results indicate that FPH enhanced the antioxidant activities and affected some characteristics due to less interaction between gelatin and FPH. [ABSTRACT FROM AUTHOR]

Background. Loach fishes, Cobitis sp., are found in the majority of streams in the southern Caspian Sea basin, but reproductive parameters of them are barely known. Reproductive conditions are key parameters of fish populations and their assessment is very important for several reasons. Therefore, the main aim of this study was to obtain reproductive characteristics of this fish which will be a first report for the basin. Materials and methods. Sampling was done at monthly intervals throughout the year and 226 individuals of Cobitis sp., were caught from the Babolrud River in the southern Caspian Sea basin, north of Iran. Age, sex ratio, fecundity, oocytes diameter, gonadosomatic- and modified gonadosomatic indices were estimated. Regression analyses were used to find relations between fecundity and fish size (length and weight), gonad weight, and age. Results. Sex ratio differed significantly from unity, and the percentage of females was greater than that of males. The mature females and males were longer than 45 and 35 mm in total length (+2 and +1 in age, respectively). The average egg diameter was 0.58 mm. The spawning took place from beginning of May to late July, when water temperature was between 19.1 and 24.6°C. Average GSI value at the beginning of the reproduction period was 8.93% and ranged between 4% and 26% in ripe, mature females. The average of absolute and relative fecundity was calculated 2172 and 590, respectively. The absolute fecundity was significantly related to body weight and gonad weight. Conclusion. Based on the pattern of gonadosomatic index, it was concluded that this fish has a prolonged active reproductive period. Their reproduction in this basin shows some differences from other reports, which might be related to different environmental conditions. [ABSTRACT FROM AUTHOR]