نشریه علوم آبزی پروری پیشرفته
سال دوم شماره 3 (پاییز 1397)

The effects of dietary protein levels on growth and feed efficiency were investigated in Caspian trout, Salmo trutta caspius. Five experimental diets containing five different dietary levels of protein (35, 40, 45, 50 and 55% diet) were fed to triplicate groups of 225 with an initial weight of 4.85 ± 0.45 g for 63 days. Oxygen concentration was 7.6 ± 0.68 mg L-1 and average water temperature was 17.7 ± 1.5 °C was in effect throughout the experimental period. Significant higher Final body weight, weight gain, specific growth rate, protein efficiency ratio and condition factor were observed in fish fed diet supplemented with optimum levels of protein (40 and 45%) than that of fish of other dietary groups such as 35 and 55 % protein. Feed efficiency ratio of fish fed 35 and 55 % protein were significantly higher than those of fish fed 40 and 45% dietary protein levels (P≤ 0.05).  There were no significant differences in white blood cell content of serum in all treatments, expect fish fed diet containing 45 % protein that was significantly higher than that of fish fed other diets. Lysozyme activity of fish fed 55 % protein was significantly higher than this of fish fed 35 % protein.  Based on the results of this study, could say that increased levels of protein in the diets of juvenile Caspian trout (Salmo trutta caspius) up to 40- 45% in diet, improved growth performance, feed utilization parameters and nonspecific immune response.

Feed comprises the main cost and adjust the economical profit in aquaculture operations. From an economical and environmental view, it is important to ensure that feed is well utilized, providing high growth rate and good health and finally ensure a high-quality production. Fish feed is formulated in order to meet the target species needs for nutrient and energy. All ingredient combined by leas-cost formulation software to satisfy nutritional requirement of the aquatic animal. Knowing the high cost of feed in aquaculture units, highlights this point that high quality feed production in factory and best feeding management in farms, is on both side responsibilities. The farmer is in charge for best feeding administration, suitable storage and feed handling. Any neglection in this area may results economic lost and complications. Awareness of symptoms and problems caused by poor feed quality, feed spoilage and unfavorable condition causers in feed and store and quality control program care, helps the aquacultures units to optimize their practice.

This survey was an applied and survey type that their data were collected through visits of farms and completion of the questionnaire of 58 selected farms of carp in Guilan province. In terms of building pond design, 39.7% of them had suitable walls, 56.9% had a suitable slope. Rivers (62.6%) and wells (25.86%) were the main sources of water supply to the ponds, and wastewater was discharged to rivers in most cases (62.1%). The physical filtration of the input water, water tank and sediment pond was available in 26.3%, 19.3% and 1.7% of the ponds, respectively. Principal preparation steps in most ponds were not fully implemented.In all the farms, fish were fed from the province and in 58.6% of the farms were co-isotherm before the introduction of fish to the pond was well respected. 53% of breeders made fish meals handmade. Cow and poultry fertilizers Urea and phosphate are the most widely used fertilizers in fields but the use of these fertilizers in most cases is non-compliant with Fisheries instructions were carried out. Non-target living factors were seen in most of farms and there was no serious program to control them. Health sampling was carried out only in 10.3% of the farms. Most farmers had no academic education, while a limited number of them had completed training courses. Only 10.3% of the farms benefited from the technical expert. A review of the questionnaires shows that there are many weaknesses against some of the valuable experiences of this industry's activists. The responsible organizations can play an important role in eliminating of many problems and increasing the production and income of the producers by taking advantage of experts’ opinions and providing essential and applied training.

The purpose of this study was to isolate and cultivate of microalgae enrich of fatty acids in order to improve the composition of fatty acids in daphnia. Scenedesmus dimorphus and Chlorella vulgaris were isolated and cultivated.  For this study two treatment groups and one control group (with three replicates) were considered. Daphnia in treatments 1 and 2 were fed with S. dimorphus and C. vulgaris, respectively and control group didn’t feed any algae. The microalgae density to enrich of daphnia was 5×107 cells/ml. Daphnia enrichment was carried out for 24 hours. On the basis of results, the amounts of PUFA in S. dimorphus and C. vulgaris were %16 and %26.3 respectively. The amounts of unsaturated fatty acids of Eicosapentaeonic acid (C20:5) and Docosahexaenoic acid (C22:6) in S. dimorphus, were %0.8 and %1.1 respectively. The amounts of the Linoleic acid (C18: 2) and Linolenic acid (C18:3) in C. vulgaris were %8.6 and %16.9 respectively. The PUFA amounts in control group, daphnia enriched with C. vulgaris and daphnia enriched with S. dimorphus were %15.1, %17.6 and %19.8 respectively. Enrichment of Daphnia with the mentioned algae was effective in improving fatty acids composition of daphnia.

This research aims to investigate the effect of three types of water inlets (one vertical input; two vertical inputs; one vertical & horizontal input) on the rate of water exchange and solid removal in octagonal reservoir (313 liter, without fish). Entering water in all entrances was 0.086 liter per second (water exchange: once per each hour). Salt was used as the tracer in measuring water exchange of reservoirs and the polystyrene was used as the simulator of fish waste. After one hour, in octagonal reservoir with two vertical inputs, salinity was reduced from 20 to 6.40±0.20 ppt and with one vertical & horizontal input from 20 to 6.67±0.05 ppt that had effective in water exchange. And in circular reservoir with vertical & horizontal inputs, salinity was reduced from 20 to 9.30±0.20 ppt that had effective in water exchange. In two reservoirs, discharge rate of polymer granules (waste) over time increased and then decreased. Maximum polymer granules discharge rate was observed in octagonal reservoir with one vertical input (44.20 ± 0.88 g) and in the circular reservoir with one vertical & horizontal input (38.5 ± 3.97 g). The results of the interaction between the input method and the type of reservoirs showed that the most effective input for the water change rate belonged to: one vertical & horizontal input > two vertical inputs > one vertical input, respectively. While the most effective solid removal were: one vertical input> one vertical & horizontal input > two vertical inputs, respectively.

In this research,were evaluated 50 gonad pieces at age 3 and 4 year old , farmed huso huso in concrete pools of Shahid Rajaee Reproduction and Rearing Sari were 25 pieces (14 females and 11 males) by biopsy in the winter 2003. Anesthetizing fish was used with clove powder. Microscopic slides were prepared by microtome 5-7µ and then the histological slides were stained with Hematoxylene & Eosin. Microscopic studies showed that 54% of the fish (27 pieces), 46% (23 pieces) male and were detectable of sexual maturity in terms. Also, in this study, 25 pieces of the Shahid Rajaee, 56% of the were males, 44% females, and including 3 stages I- II (28.57%), stage II (50%) and stage II- III ( 21.42%) and in males 5 sex stages included stage I- II (9.88%), stage II (18.8%), stage II- III (18.8%) and stage III-IV (27.3%) and stage IV (27.3%) observation Became Of the 25 pieces of the Gorgan Shahid Marjani, 52% were female and 48% were male. Sexual maturity of the four sexual stages in the females including stage I (15.8%), stage I- II (30.76%) stage II (38.44%) and stage II-III (15.38%) and in males three sexual stages Including stage II (58.3%), stage II-III (25%) and stage IV (16.66%) were detectable. Our studies showed that according to age, environmental conditions and maintenance, these fishes were in the proper position and desirable sexual maturity in term.