مجله علمی شیلات ایران
سال سی و یکم شماره 5 (پیاپی 133، آذر و دی 1401)

In the present study, the effects of different probiotics mixtures on growth performance, hematology and antioxidant capacity of Asian seabass (Lates calcarifer) juveniles (30 g). In this study, three bacterial mixtures were used that were isolated from the native aquatic species of Khuzestan and the South of the country, which include: the first group includes different strains of Lactobacillus plantarum, the second group includes L. plantarum with a mixture of L. bulgaricus, L. acidophilus and L. rahamnosus and the third group includes the mixture of bacteria of the first and second groups along with the mixture of Bacillus cereus and B. thuringiensis, which were identified through their quorum quenching features and isolated from Asian sea bass. Four treatments were designed by spraying various bacterial mixture on a basal diet, which included diet (1, control group) on which only sterile physiological serum was sprayed on the diet, diet (2) on which the bacterial mixture of the first group was sprayed on the diet, diet (3) on which the mixture of bacteria of the second group was sprayed and diet (4) which was the mixture of all bacteria was sprayed on it and fed to the fish. The fish was fed with the experimental diets four times a day up to satiation at 30.5 °C for 100 days. In this study, the fish that was fed with 2, 3 and 4 diets had a higher growth performance than the control (p < 0.05), which was associated with an improvement in the food conversion ratio. Blood and antioxidant indices were improved in the fish fed with diets containing probiotics mixture. Treatment 4 had more total plasma protein and albumin than other treatments. In conclusion, the use of a mixture of different probiotics increased growth in Asian seabass that associated with improved health indices in this species.

The production of all-female monosex rainbow trout through the production of sex reversed male breeders by hormone therapy has several advantages, and in previous years, delays in the localization of this technology has led to the country's dependence on imported eyed eggs. In this research, the native rainbow trout fry and the fry from all-female imported eggs were fed with a diet containing 3 mg/kg of the hormone for 70 days in order to make it possible to use the imported fish stocks for breeding and also the appropriate concentration of hormone therapy using 17 alpha-methyl testosterone. The results showed that all native fish were sex reversed to male and half of the breeders (XX male) were able to produce the gynogene sperm, exclusively. The results of hormone therapy of fish produced from the imported all-female eggs were about 57% male and 43% female. The male fish at age 22 months were neomale (sex reversed male) and capable of producing sperm and fertilizing eggs but female fish had undeveloped and small ovaries. In addition to the indirect production of all-female fish, this study can facilitate the use of the genetic potential of the fish from imported monosex all-female eggs through sex reversing and mate with native fish stocks and increase the genetic diversity of progenies of native fish stocks that be used in base population production in breeding programs and cold-water fish farms.

Evaluation of microbial indicators of water resources such as rivers, seas, and dams is important because these microorganisms can change the quality and sanitary of water and also affect the quantitative and qualitative changes of other organisms. In this study, the distribution of indicator bacteria including heterotrophic bacteria, coliforms, and fecal coliforms was investigated in the headwaters of the Qeshlaq and Gawh Roud rivers of the Javah dam in Kurdistan Province. The investigated stations include upstream of the Qeshlaq, Qeshlaq river branch 1, Qeshlaq river branch 2, Gaveh Roud branch, and Sirvan branch. The results showed that the mean and standard deviation of the heterotrophic bacteria in autumn 2020, winter 2021, spring 2021, and summer 2021 in five stations were 7.300±0.22, 6.54±0.63, 7.08±0.67, 7.58±0.32 CFU/100 mL, respectively, the coliform count was 4.11±1.07, 3.61±1.27, 4.48±0.55, 5.23±1.22 CFU/100 mL, respectively, and the counting fecal coliforms count was 2.84±1.07, 3.042±0.79, 2.86±1.18, 3.44±1.98 CFU/100 mL, respectively. The pollution of the river exceeded the standard range, which is caused by the inflow of rural sewage from agricultural fields and the inflow of sewage from agricultural areas. In this research, the most polluting resources of the Qeshlaq and Gaveh Roud rivers were the untreated sewage of Sanandaj city, but other contamination resources such as sewage from livestock, various poisons, and fertilizers resulting from the agricultural activities, washing, and soil erosion cannot be ignored. One of the suggested solutions to reduce the number of indicator bacteria from the Qeshlaq river is optimizing the sewage treatment plant process and completing its construction and equipment.

About 30 species of commercial fish have been caught in the seawater of Guilan province annually and the most important species is Kutum (Rutilus frisii). The aim of this study was to determine the feeding indices, food spectrum, and dominant food items of fingerlings kutum under the investigation of feeding habits of kutum and grey mullets on the coasts of Guilan province. The fish were captured with a seine net with 6 mm mesh size from winter 2020 to autumn 2021 in the coastal areas of Talesh, Anzali, Kiashahr, and Chaboksar. The results on R. frisii with body weight 0.31-14.5 (3.64±2.8)g, total length 34.3-120 (68.3±19.0) mm and ages 0+ and 1+ years showed that the relative length of intestine is 0.59-1.16 (0.78±0.10). Vacuity index was calculated at 0, 0, 5, 0 and 1% in spring, summer, autumn, and winter seasons and the total of the year, respectively, and the mean fullness intensity was 372±267, 360±151, 230±173, 581±689 and 365±302 in spring until winter and total of the year, respectively, which showed significant differences (F=9.10, p<0.05). Detritus, filamentous algae, 26 genera of phytoplankton, 2 types of zooplankton and 13 types of benthic animals and as well as eggs and larvae of fish were observed in the gastrointestinal tract of kutum fingerlings with a frequency of presence 10, 73, 62, 5, 86 and 2 percent of all studied specimens, respectively. The phytoplanktonic genera of Cyclotella, Navicula and Nitzschia were observed in 60%, 52%, and 47% respectively, and gammaridae among the benthic animals had the most frequency in 68% of the fish. In general, according to the feeding indices, feed diversity, and dominance of feed items, kutum fingerlings are a benthic feeders and euryphagous with a good fullness intensity on Guilan coasts.

The present study aimed to evaluate the protective effect of vitamins E and C on reducing the effects of dietary oxidized fish oil on the growth, hematological and biochemical indices of rainbow trout fry. For this purpose, 240 fries with an average weight of 12.75±0.25 g were fed with 4 treatments including, treatment 1: a diet containing fresh fish oil, treatment 2: a diet with oxidized fish oil, treatment 3: a diet containing oxidized fish oil along with the low level of vitamin supplements (100 mg/kg vitamin E, 200 mg/kg vitamin C) and treatment 4: a diet with oxidized fish oil along with the high level of vitamin supplement (200 mg/kg vitamin E, 400 mg/kg vitamin C) for 60 days. At the end of the trial, the indices of specific growth rate (SGR), weight gain percentage (WG), and food conversion ratio (FCR) were calculated. Also, the hematological and serum biochemical parameters: cholesterol, triglyceride, high density lipoprotein (HDL), and low density lipoprotein (LDL) were measured. Based on the obtained results, the SGR and WG, were decreased in 2, 3 and 4 treatments and the FCR was increased (p<0.05). The white blood cells (WBC), red blood cells (RBC), hemoglobin (Hb), and hematocrit (Htc) levels were increased in 2, 3, and 4 treatments (p<0.05). The triglyceride and HDL contents were increased in 3 and 4 treatments, respectively (p<0.05). Also, there were not significant differences between different treatments for serum cholesterol and LDL indices (p>0.05). Finally, it was concluded that oxidized fish oil has adverse effects on growth, hematological and biochemical indices, and the vitamin supplements are effective in reducing these effects on the hematological and biochemical parameters.

In the current study, to obtain length indices for the sustainable fishing management of Caspian roach, the LBB (Length-Based Bayesian Biomass Estimator) model, which is a new and powerful but simple solution based only on the length data, was used. Three important management indicators including length at the first catch (Lc), optimum length at the first capture (Lc-opt), and optimal length of capture (Lopt) were estimated, and their values were 17.7, 21 and 24 cm, respectively. The values of Lmean/Lopt and Lmean/LF=M ratios were almost smaller than 1, which indicated the optimal yield is not performed. In this study, Lc/Lc-opt ratio was less than 1 and Lmax5%/Linf or L95%/Linf indice was smaller than 0.8 and the number of megaspawners less than 1% and the percentages of specimens at the optimum size of less than 10% were estimated. These findings indicated the absence or presence of a few old and large fish in the stock, and the broodstock population has been reduced to a level where it no longer has the reproductive capacity to revive itself. Caspian Roach was preserved to a great extent based on  = 14 cm due to a very low percentage of immature fish (less than 5%) in the catch and L25%/L50>0.3, Lmean/L50>1, and Lc/L50>1. According to the findings of this research, including the optimal length of capture in the management procedures will probably have a better relative performance for the conservation and sustainable exploitation of Caspian Roach.

This study was aimed to determine the effect of different levels of dietary rainbow trout (Oncorhynchus mykiss) visceral protein hydrolysate on growth performance, carcass composition, digestive enzymes, and bacterial flora of juvenile Siberian Sturgeon (Acipenser baerii). For this purpose, 300 juvenile Siberian Sturgeon with an average initail weight of 67±3 g were distributed in 12 tanks with a volume of 2000 L. 25 fish was introduced in each tank and were fed with different levels of protein hydrolysate (PH) in 4 treatments including 0 (control), 5 (5PH), 10 (10PH) and 20 (20PH) g of protein hydrolysate per kg of feed for 56 days. Based on the results, all growth indices improved in all treatments containing PH compared to the control (p<0.05) and the highest specific growth rate, weight gain and weight gain percentage were in 10PH and showed a significant difference compared to others (p<0.05). In this study, the lowest rate of feed conversion ratio was observed in 10PH and the highest rate was observed in the control. Fish fed with 10PH had also the highest amount of crude protein (19.10±0.14%) and the lowest percentage of lipid (5.60±0.15%). The results showed that the amylase and lipase enzyme activitites in 10PH treatment was significantly higher than other treatments (p<0.05). Also, trypsin enzyme activity in 10PH was significantly higher than the control and 5PH (p<0.05). The number of lactic acid bacteria in the treatment 10PH showed the highest numbers (p<0.05). In general, the effect of visceral protein hydrolysate, especially in treatment 10PH, on the growth indices, body composition, digestive enzymes, and the number of intestinal lactic acid bacteria of juvenile Siberian Sturgeon was positively and significantly evaluated and this treatment is recommended to improve the investigated parameters.

This study investigates the Artemia biomass and cysts changes in Urmia Lake in different time periods. However, changes in Artemia population in other hypersaline lakes such as the Great Salt Lake of America, Dead Sea and Griessmeir lake in Newzeland have also been investigated. The first documented estimation of Artemia stock in Lake Urmia was made by Gϋnther about 125 years ago. After him, in various time periods, Urmia Lake Artemia population was assessed by different authors. The most important researches of them were the studies which performed in last three decades. The highest Artemia population in Lake Urmia has been reported in 1990s which was simultaneous with the highest water standing level of the lake. Here after the lake water level was steadily declined, which negatively affected Artemia communities. In 2010s, Lake Urmia was faced with a water shortage crisis so, Artemia population declined dramatically. Regarding the Great Salt Lake similarities to Urmia Lake, this lake investigation were highlighted in our research. Generally, Artemia cysts density in Urmia lake were decreased from 2500 per liter in 1990s to 4.6 in 2010s, and the biomass from 1500 per cubic meter in 1990s to 4 per cubic meter in 2010s. Lowering the lake water level and simultaneously increasing its salinity is recognized as one of the most important factors in the Artemia population drop. Another crucial parameter in Artemia population decline in Lake Urmia is the significant reduction of algae population, particularly Dunaliella, which is the main food source of Artemia.

The mucus secreted from the epidermis of fish is the first line of defense against pathogens and protects them from the risk of invading pathogenic microorganisms. The purpose of this study is to investigate and compare the three factors of mucus concentration, season, and sex in order to evaluate the antibacterial properties of the secreted mucus from a mudskipper (Periophthalmus waltoni) on four strains of standard bacteria including Escherichia coli (25922), Staphylococcus aureus (6538), Bacillus subtillis (6633), and Pseudomonas aeruginosa (9027) in both hot and cold seasons. Mucus was collected from the surface of fish skin and its antibacterial activity was evaluated by disc diffusion method . Also, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined against the two bacteria that showed more sensitivity. The results showed that in both seasonal periods and in all the studied bacteria based on the concentrations (200, 100, 50, 25 mg/ml) prepared from the extracted mucus the average diameter of the growth zone diameter was increased with an increase in the extracted mucus concentration, and the Gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa, were the most sensitive and resistant bacteria to the extract, respectively. From the antibacterial investigations of the mucus on the standard strains based on the seasonal factor, the mucus obtained in the warm season period had higher antibacterial properties than the mucus obtained in the cold season period (p<0.05). The average diameter of the growth zone against the studied bacteria was greater in females than males, although it was not significantly different (p>0.05). The antibacterial effects of the fish mucus depended on the mucus concentrations  (200, 100, 50, 25 mg/ml) and also, the amount of mucus secretion was significantly affected by seasonal changes and gender.

The purpose of this study was to evaluate the toxicological effects of lead on hematological and biochemical indices of common carp. For this purpose, 90 fish were exposed to two sub-lethal levels (1.3 mg/l and 2.6 mg/l) for 21 days. Then, the blood samples were taken to measure the cortisol, cholesterol, triglyceride, red blood cells, white blood cells, hematocrit, and hemoglobin. The amount of cortisol and total white blood cells in the group exposed to 2.6 mg/l of lead were 12.03±2.30 μg/dl and 23.10±0.25×103/ mm3, respectively, which were significantly decreased compared to the control group. Compared to the control group, cholesterol and triglyceride levels were significantly higher in the group exposed to 1.3 mg/l, (178.50±3.17 mg/dl and 341.38±5.87 mg/dl, respectively). A decrease in the values of hemoglobin, hematocrit, and red blood cells indicates anemia in the exposed fish.