نشریه پژوهش های ماهی شناسی کاربردی
سال یازدهم شماره 2 (تابستان 1402)

More than 50 fish species exist in Guilan coast waters and 20 species of them are economic, but there is few data about their fingerlings. This study has been done in Talesh, Anzali, Kiashahr and Chaboksar shores and fish seasonally caught by beach seine with 8 mm mesh size from winter to autumn 2021, and the main purpose was determining fish abundance in Guilan province coasts, too. Results showed 32 fish species belong to 13 families in studied are and Leuciscidae family was the most diversified with 8 species. The study of fish abundance showed dominancy of Chelon saliens, Alburnus chalcoides and Atherina caspia with 42.5%, 18.1% and 11.6% in Talesh shore, A. chalcoides, C. saliens, and A. caspia with 25.1%, 22.1% and 20.8% in Anzali shore, C. saliens, Rutilus frisii and A. chalcoides with 31.8%, 17.4% and 14.8% in Kiashahr shore and C. saliens, A. chalcoides, Neogobius pallasi and chelon auratus with 29.9%, 21.5%, 14.2% and 10.5% in Kiashahr shore, of total count (number), respectively and they were predominant. In general, were abundant fish, the fingerlings to non-adults of sharp-nosed grey mullet (Ch. saliens) and Shemaya (A. chalcoides) in all stations, Caspian silverside (A. caspia) in 2 stations and fingerlings of Golden grey mullet (Ch. auratus) and Kutum (R. frisii), and fingerlings to adults of Caspian sand goby (N. pallasi) in one station, that show a more adaptation of these species to environmental conditions in 4 studied stations. The continuous monitoring of density of small size individual of fish species in southern coasts of Caspian Sea is essential for conservation of their populations.

The purpose of this research was to investigate the catch composition and length frequency of S. putnamae using Four meshe sizes of 64, 83, 95 and 110 mm in gillnet in the February (winter) and June (Summer) 2022, in the coastal waters of Sistan and Baluchistan province. In the Sampling period, 22 species were caught, in the summer season, the highest catch rate was 33.04% for the S. putnamae and P. pelagicus was the least caught with 0.37% , and in the winter season, S. putnamae was the most caught with 35.68% and T. croaker the lowest catch rate of 0.31%. Also, The rate of by-catch was 17.10%, A. thalassinus the highest percentage of by-catch. The highest length frequency with 52.8% for 83 mm mesh size in the summer and the highest length with 57.2% for 95 mm mesh size obtained in winter. the comparison of the length frequency of S. putnamae caught by different mesh sizes in summer and winter season and the average length of S. putnamae in the different mesh sizes showed that there is a significant difference between them. Also, the comparison between the mesh sizes showed that the 83 mm mesh size in summer and the 95 mm mesh size in winter had a significant difference with the size of other and similar mesh size in other seasons. The results showed that more fish were Snagged in smaller mesh size and more fish were Gilled in larger mesh size.

This study was conducted to estimate length-weight parameters of obtuse barracuda (Sphyraena obtusata) in fishing grounds of the Persian Gulf and Oman Sea (Hormozgan province) during 18 months from September 2019 to February 2021. Sampling was done using mid-water trawlers, Goshgir and Moshta nets. Totally, 443 samples including 206 males and 237 females were subjected to biometric measurements and sex determination. Investigating growth curves using theoretical informative approach of MMI revealed that a three parameterized Von Bertalanfy and two parameterized Von Bertalanfy were the best models fitting to describe the growth of males and females obtuse barracuda (S.obtusata), respectively. Regarding growth models tested in the present work, L∞, K, and the birth size were 30.34 cm, 0.485 y-1 and 10.38cm for female obtuse barracuda, and 28.27 cm, 0.56 y-1 and 9.41 cm for male obtuse barracuda. According to likelihood method, growth curves of male and females were significantly different (p<0.05). growth performance index (phi-prime, φ') were 2.64 , 2.65 and 2.61 for males , females and total population. Findings presented here showed that using a MMI approach and testing various models are recommended to better understand and select the best growth model of the commercial and valuable species obtuse barracuda (S.obtusata).

This research was conducted with the aim of investigating the effect of nettle powder on the growth and survival indices and liver enzymes in the blood serum (ALP, ALT, AST and LDH) of common carp juveniles. For this purpose, 180 common carp with an average weight of 5.41 ± 1.58 grams were prepared and kept in laboratory conditions for one week before the start of the experiment and fed with a commercial diet without nettle powder. Then, the fish were completely randomly divided into four treatment groups containing 0 (control), 1, 2 and 3% of nettle powder per kilogram of diet and three repetitions for each treatment, during a period of eight weeks, based on 3% of their body weight. At the end of the experiment period, the results showed that the growth indices in the treatment of 3% nettle powder with the average growth rate )11.46±2.06 (and the food conversion ratio )2.98±0.03(significantly decreased compared to the control treatment (p<0.05).The highest percentage of survival rate was observed in the 3% nettle powder treatment (77.77±3.84%), which showed a significant difference compared to the control treatment (p<0.05). Also, there was no significant difference between the treatments in the chemical composition of the tested fish carcasses (p>0.05). The examination of liver enzymes in the blood serum of fishes showed that the level of AST enzyme activity in fishes fed with 3% nettle powder had a significant increase compared to the fishes of the control group (p<0.05). In general, the results showed that nettle does not have a positive effect on growth and feeding efficiency in carp.

The ability of fish adaptation to different salinities depends on osmotic, ionic and biochemical regulation, on the other hand, transferring fish to salt water causes the development of their osmotic and ionic homeostasis mechanism. The adaptation of stellate sturgeon (Acipenser stellatus) in four weight treatments including 0.5-1, 1-3, 3-5 and 5-10 g in water with four salinity levels of 0.5, 4, 8 and 12 g/l during 8 phases and each experiment was performed in 4 predicted treatments. Each experiment was carried out in a period of about one month along with feeding with live foods, preferably gammarus, Nereis worms, and chironomidae larvae at the saturation level of 6 times a day, as well as daily siphoning and water changes. Osmolarity and factors of chloride, calcium, sodium and potassium were measured in fish blood serum. In the examination of the compatibility and adaptability of this fish with the conditions of changing salinity, the results showed that with increasing salinity, the levels of potassium, sodium, chloride and blood osmolarity increased. The stellate sturgeon are able to adjust the osmotic pressure and ionic composition of their blood serum when they migrate from hyperosmotic to hypoosmotic environment or vice versa. The blood osmolarity of fish with a weight of 5-10 g was higher than other weights, and the lowest osmolarity was observed in fresh water (0.5 g/l). The results of this study showed that the amount of potassium in the blood serum decreased with the passage of time and the increase in salinity, and increased the amount of sodium and calcium in the blood serum.

In this study the combined effects of photoperiod and compensatory growth on growth, hematology indexes, biochemical indexes, cortisol and lysozyme of rainbow trout were investigated. In this regard, 552 specimens of rainbow trout fingerlings )8± 0/9gr (were treated with different photoperiod regimes (LD 06:18, LD 12:12, LD 18:06, and LD 24:00) with intermittent periods of satiety and starvation (4 days starvation and 4 days refeeding for 60 days) in compared to control groups. In photoperiod regimes 24 h light had the highest growth and food intake efficiency, but 6 h light treatment with compensatory growth had the lowest feed conversion ratio in compare to other treatments. The 4 days of starvation reduced amount of biochemical parameters and the light did not cause any changes in these parameters. In terms of 24 h of light regime, Hct (33/04%), Hb (9/43g dL-1) and RBC (1/31*106Ml-1) amounts were significantly higher than other treatments, but lysozyme level was not affected by light and starvation treatments. Also, cortisol levels during starvation (4 days) were significantly higher than 4 days refeeding. According to the results, the treatment of 6h of light in both photoperiod techniques alone and the combination of photoperiod with compensatory growth was determined as the optimal treatment.

The aim of this study was to investigate the potential of using saffron petal powder on the growth performance and innate immune parameters of the skin mucus of rainbow trout. For this purpose, 600 rainbow trout juvenile (6.6 ± 0.19 g) were randomly divided into four experimental groups and fed with diets containing 0, 0.5, 1 and 2% raw powder of saffron petals for 8 weeks. The results showed that feeding juvenile with a diet containing 0.5% saffron petal powder led to a significant improvement in growth indicators including gain weight, specific growth rate and factor condition compared to the control group. The results showed that the juvenile fed with a diet containing 0.5% saffron petal powder led to a significant improvement in growth indicators incliding weight gain, specific growth rate and condition factore feed conversion ratio compared to the control group, while, higher concentrations (1.5 and 2%) had no significant effect on the growth performance. The analysis of the innate immune parameters of the skin mucus also showed lysozyme enzyme had a dose-dependent increase, so that its highest level was observed in the treatments fed with ration containing 2% saffron petal powder. The analysis of the innate immune parameters of the skin mucus also showed that the lysozyme enzyme had a dose-dependent increase, so that its highest level was observed in the treatments fed with a diet containing 2% saffron petal powder. Also, the highest level of hemagglutination activity and antibacterial activity against two common pathogenic bacteria in aquaculture, including Yersinia rookeri and Aeromonas hydrophila, was related to the treatment fed with a diet containing 2% saffron petal powder. Therefore, saffron petal powder, especially at a concentration of 0.5%, has the potential to be used as a growth and immune stimulant with natural origin, cost-effective, efficient, and eco-friendly immunostimulant in rainbow trout farms to improve the level of aquatic health and increase resistance to common bacterial infections, including enteric redmouth disease and bacterial hemorrhagic septicemia.

Since aquaculture is directly related to human food and water resources, we need to use new techniques to realize sustainable aquaculture. One proposed solution to achieve sustainable aquaculture is to increase the density and improve the diet of farmed fish. The present study investigates the effect of coenzyme Q10 (CoQ10) in the diet on the growth, carcass composition, and ammonia stress of rainbow trout Juveniles. To this end, fish were fed diets containing zero, 0.1, 0.5, and 1% CoQ10 levels for two months. At the end of the breeding period, growth and hematology indicators were calculated, and the carcass composition was analyzed. Ammonia stress was induced at a concentration of 0.6 mg/liter at the end of the study. The findings reveal that adding 1% CoQ10 to the diet before stress leads to increased growth, reduced carcass fat, and increased white blood cell count (p<0.05). Additionally, after ammonia stress, CoQ10 creates resistance in fish, resulting in significantly reduced losses (p<0.05). In general, it can be concluded that CoQ10 can be effectively used in aquaculture to increase growth and improve the ability to tolerate stressful conditions, particularly those caused by an increase in ammonia levels. Furthermore, CoQ10 can be utilized during dense and ultra-dense breeding to enhance growth and increase tolerance to stressful conditions, such as an increase in ammonia levels. As a result, CoQ10 can be used in breeding farms to significantly reduce losses by preventing damage to blood cells and maintaining the oxygenation process.