دکتر غلامرضا رفیعی

Frozen food products obtained from aquatic animals during freezing or storage in the cold room can experience a loss of quality due to the direct contact of oxygen and cool air of the cold room. Nowadays, glazing technique is used to prevent or slow down the quality loss of frozen aquatic animals stored in cold storage. Glazing is a method that is widely used to preserve the quality of frozen seafood against the effects of long-term storage in cold storage. In this process, a layer of ice covers the surface of frozen aquatic products such as fish, which prevents contact between the air and the surface of the product and preserves their quality during transportation and storage in cold storage. This ice cover prevents the direct contact of oxygen and cool air of the cold room with the surface of the food product, and as a result, reduces the rate of oxidation, dehydration, freeze burn, etc. of the product. The thickness of the ice coating depends on many factors such as the duration of glazing, the initial temperature of the frozen food product, the temperature of the solution used for coating, and the characteristics of the product itself, including the amount of product surface, its shape and size. Keeping the product quality is affected by the thickness of the ice cover and the weak ice cover practically does not provide its protective function correctly. In this article, various glazing methods have been introduced, the factors affecting the thickness of the ice cover, its disadvantages and advantages compared to the usual methods of packaging seafood products, and the causes of some glazing problems and their solutions have been discussed. In this article, different glazing methods have been introduced, factors affecting the thickness of the ice coating, disadvantages and advantages of different glazing methods.

The aim of this study was to investigate the effect of different dietary inclusion levels of replacing natural carotenoids derived from carrot powder (0, 25, 50, 75 and 100%) with synthetic astaxanthin on the carcass quality indices of rainbow trout (Oncorhynchus mykiss). A completely randomized experimental design with 5 treatments and one control treatment, each with 3 replications, was employed in this study. The 306 fish with an average initial body weight of 50±/030 g were randomly allocated to 18 experimental fiberglass tanks. The breeding period was 60 days. At the end of the culturing period the fishes were stored in cold temperature (4°C) for 16 days. The results showed that adding natural carotenoids through carrot powder to fish feed had a significant effect on the carcass quality indices (P<0.05). The rates of TVB-N, TBA, WHC and pH indices in treatments revealed that replacing 50 and 75% natural carotenoids for synthetic astaxanthin in the diet significantly reduce the rate of fish spoilage over the cold storage period (P<0.05).

The present study was conducted in Chapkrud Joibar fish rearing farm and the effect of plankton and fertilizers transferring to the ponds and their effects on growth, survival of carps and plankton changes in pond were investigated. The ratios of C:N:P 88.6:7.5:1 adjusted for all treatments. The treatments consisted of 1- fertilization with 6000kg/ha per year, 2- fertilization with 12000kg/ha per year, 3- fertilization with 6000kg/ha/year and phytoplankton treatment and 4- fertilization with 12,000kg/ha per year and phytoplankton treatment. At the end of this experiment, treatment 4 provided the best growth conditions for rearing of carps. The highest initial production and number of phytoplankton per unit were observed in treatments 4 and 3, respectively, and had a significant difference with treatments 1 and 2 (P<0.05). The Ankyra, Chlorella, Scenedesmus, Tetrastrum, Spirogyra, Navicula and filamentous algae had the highest frequency of phytoplankton in ponds as primary productions. The main zooplanktons and benthos of the ponds were Rotifer, Daphnia, Copepoda, Seratopogonide and Vetivolid. Therefore, according to the research objectives, increasing the production per unit area and optimizing the amount of fertilization in pond. Treatment 4 including plankton, and fertilization with concentration of 12,000kg/year had the best results, which if it mixed with vermicompost fertilizer will improve the carps culture system.

Despite the development of polystyrene nanoplastics (PSNPs) in different fields, including nanotechnology, environment, industries, and their possible approach to aquatic ecosystems, a few studies have been conducted on nanoecotoxicology in aquatic animals. Therefore, this study was designed and conducted to measure the effect of toxicity of the PSNPs while transferring from the diet to the body of the fish (food concentrations= 0.1, 10, and 100 mg/kg) on juvenile rainbow trout (Oncorhynchus mykiss) in a 28-day chronic treatment and the control group (food concentration = 0 mg/kg) after the 7-day adaptation period, in three repetitions (15 juvenile trout were included in each repetition per concentration). Depending on the target test, fish sampling in the treatment group was taken after 24 h without food. According to the results, the survival rate (SR) (84.44 ± 3.14%) was significantly reduced with the highest dose of PSNPs compared to other treatments (P<0.05). But other growth indices did not show statistically significant difference (P>0.05). From the point of view of tissue pathology of polystyrene nanoplastic in the liver tissue in treatment 3 and 4, injuries such as vacuolation, necrosis, sinusoidal expansion and pyknotic nucleus were observed in rainbow trout. Based on the obtained results, the negative effects of polystyrene nanoplastic release on health and immunity at the cellular level were seen in liver histology in the studied aquatic sample. In general, this study showed that the entry of nanoplastic particles through the digestive tract causes changes in the histological parameters of the liver. However, more comprehensive studies are needed in this field.

In this study, the effects of different levels of dietary supplementation with probiotic (BioAqua) and soy-bean lecithin on reproductive efficiency (absolute and relative fecundity, number of eggs per gram, egg diameter, percentage of fertilization and percentage of eyed-egg) of female rainbow trout (Oncorhynchus mykiss) were investigated. For this purpose, the broodstock (2.73±0.02 kg) were fed with 5 different experimental diets including control, B2L6 (2 grams/kg of BioAqua probiotics and 6 percent soy lecithin), B2L9, B4L6 and B4L9 with the rate of one percent of their body weight once a day (at 10 A.M) for two months. The highest absolute   relative fecundity, percentage of fertilization, and percentage of eyed-egg were significantly different in B4L9 treatment (7153.01±76.89, 2604.23±23.77, 99±1%, and 97.33±1.15%, respectively) compared to the control treatment (5304.64±143.09, 1950.05±26.46, 93.33±1.15% and 91±1%, respectively; P<0.05). Also, the largest egg diameter was recorded in B2L9 and B4L9 treatments (5.01±0.07 and 5.05±0.04 mm, respectively), which were significantly different from other treatments (P<0.05). Furthermore, the lowest number of eggs per gram was obtained in B4L9 treatment (15±0.3), which had a significant difference with the control treatment (17.2±0.4; P<0.05). The absolute and relative fecundity and number of eggs per gram in B2L6, B4L6 and B2L9 treatments were not significantly different (P>0.05). The result of the current study revealed that simultaneous dietary supplementation of at least two grams per kilogram of BioAqua probiotic along with at least six percent soy-bean lecithin improve the reproductive efficiency in female rainbow trout.

In this study, using different biological factors, we tried to remove the fish metabolites and improve the water quality in the culture system. Therefore, operation of some recirculating system were investigated during a 2-month culture period. The biological factors were bacterial (aerobic and none aerobic bacteria, in two separate departments), Lemnea plant and hetrotrophic bacteria for formation of biofloc with adjusting the ratio of C/N. The treatments included 1- a system consisted of the plant (P), 2- a system comprised the plant and biofilter (PB), a system containing of the plant, biofilter and biofloc (FBP) and finally, a system without biological compartment just physical section as control. Twenty tilapia fingerlings (10 ± 0.5 g) were introduced in each experimental unit. The results indicated that efficiency of FBP system based on food conversion ratio, specific growth rate and survival was significantly higher than other culture systems (p<0.05). The fish were died at the 23th day of initiation of the study in the control system. The rate of Lemnea plant in the treatment P was significantly higher than in other treatments (p<0.05). The concentrations of Ca, P, nitrate, ammonia, nitrite and pH were significantly different among treatments. So that, these minerals in treatment FBP were lower than those in the other treatments at the end of the study. The results indicated that using different biological methods (together) in a tilapia culture system could be more efficient in the removal of fish metabolites, in addition to the improvement of fish growth and plant in an integrated fish and plant culture system.

The present study was conducted to assess the water quality of the Balighli-Chai and Ghare-Sou Rivers, the main rivers of Ardabil Province, Iran. The levels of dissolved oxygen (DO), biochemical oxygen demand (BOD), nitrate (NO3) and phosphate (PO4) were measured and simulated using the QUAL2Kw model during low- and high-water periods. Also, self-purification capacity and total maximum daily load (TMDL) levels of water quality parameters were calculated. The obtained results indicated considerable differences between the levels simulated by the model from the measured data for both rivers. Most of the river sections had low self-purification capacities. Maximum self-purification capacity (%) were: high water period: DO = -226.61; BOD5 = 90/30; NO3 = 99.88; PO4 = 96.49; low water period: DO = -281.71; BOD5 = 89.13; NO3 = 94.74; PO4 = 90.21. TMDL scores for DO, BOD5 and NO3 were higher during the high-water period, but entire sections of both rivers showed high excess loads of PO4. The results showed that most ranges of both rivers didn't have appropriate water quality conditions. Therefore, it is necessary to make proper decisions to control pollution levels and improve water quality in this basin

Temperature plays an important role in physiological processes in animals. In aquatic animals, the role of temperature in embryonic development has been proved and investigation and recognition of these changes in the production of larvae and quality of fish is of great importance in the economic production dimension. In this study, the effect of water temperature changes on hatching rate and survival of rainbow trout embryo, larvae and fingerlings were investigated. The experimental treatments included of waterborne temperature 10 (control treatment), 12 (treatment 1) and 14 (treatment 2) °C in three replicates. The mean percentage of hatching in treatments 1 (85.04±0.78) and treatment 2 (84.71±1.07) were significantly higher than control treatment. (82.90±0.97) (P<0.05). The mean percentage of larvae survival in experimental treatments showed a significant increase in treatments 1 (88.24±0.78) and 2 (91.10±1.57) compared to control (80.30±1.09) (P<0.05). Also, the lowest survival rate was observed in 14°C treatment, so it can be concluded that with increasing temperature, fish metabolic rate increases and at 12°C, the survival conditions of larva and fingerlings are better, in treatment 2, this rate was significantly higher than treatment 1 (P<0.05). In the later stages of growth, it was found that the survival rate of salmon fish decreased with increasing temperature compared to the control, so that the lowest survival rate was observed in 14 °C treatment.

Most of the plastic materials used for food packaging are non-biodegradable, resulting in more environmental pollution. Hence, this study was designed and conducted to measure the effect of toxicity of the PSNPs while transferring from the diet to the body of the fish (food concentrations = 0, 0.1, 10, and 100 mg/kg) on juvenile rainbow trout (Oncorhynchus mykiss) in a 28-day chronic treatment and the control group (food concentration= 0mg/kg) after the 7-day adaptation period, in three repetitions (15 juvenile trout were included in each repetition per concentration). In addition, changes in two genetic biomarkers of the immune system and stress in the expression profile of the liver and spleen tissues indicated that following the increase in the concentration of PSNPs, the tumor necrosis factor-alpha (TNF-α) and expression level of heat shock protein 70 (HSP70) in both liver and spleen tissues significantly increased with the increase of mRNA transcription (P<0.05). Based on the obtained results, the release of NPsPS was confirmed for health and safety at the cellular-molecular level in the aquatic sample under study, and it is likely that if this nanomaterial is released in the aquatic environment, it will induce adverse environmental effects.

Considering the global consumption of frogs and providing 95% of frogs' legs at the international level through fishing from the natural environment, environmental concerns have been given more attention. Therefore, with the aim of developing the artificial reproduction of frog, the effects of using different dietary- animal and plant proteins on metamorphism of frog (Rana ridibunda) were investigated. The experimental diets were: (i) a diet containing 100% animal protein, (ii) a diet containing 100% plant protein, (iii) a diet containing 50% plant and 50% animal proteins, (iv) a diet containing 30% plant and 70% animal proteins, and (v) a diet containing 70% plant and 30% animal proteins. The tadpole fed the experimental diets in a 90-day period. The individual weight was significantly different among the treatments during the experimental period (p<0.05). The highest weight loss occurred in the 10th week of rearing in the 3, 3 and 1 treatments, respectively. Maximum weight loss was observed in the treatment 5 in the 12 week and in the treatment 2 in the week 13. Given the individual weight, and also the metamorphism process and biomass of froglets, the diet containing 50% plant and 50% animal proteins nominated more capable diet for production of froglets (Rana ridibunda).

The traditional method for staining cartilage and bone in vertebrates is to use Alcian blue and Alizarin red. Acid is used in the base of the ingredients of Alcian Blue solution, which led to clear distinguishing of the stained skeletal structures as much as possible. But the problem is that if acid is used, some of the bone ions are removed leading to errors in the results. Therefore, the present study aimed to compare two using acid and acid-free protocols for staining cartilage and bone during the early development of Common bream (Abramis brama) to provide a solution in future studies.

For staining, we applied acid-based (acetic acid) and acid-free protocols using Alican blue and Alizarin red during the processing stages of watering, staining of cartilage and bone, neutralization, watering, protein digestion, color removal, and washing and clearing.

Based on the results, it can be stated that in studies of the early development of bony fishes, the use of cartilage and bone staining method based on the acid-free protocol is more suitable than using acid because this method helps to better understand the sequence and pattern of skeletal ontogeny more accurately during the early development period.

The use of microalgae by human dates back to 2000 years ago in China, where it was used as food to survive famine. Microalgae are good sources of a wide range of beneficial compounds such as proteins, fats and pigments that have been used as food by humans for centuries. The aim of this study was examined to investigate amount of protein, fat, ash and cell growth and the total carotenoids by cultivating Dunaliella salina in Modified Johansson (DUM) and Guillard (f/2) medium under salinity stress of 100, 200, 300 ppt. The results showed that the highest protein production was 14/06 ± 0/34 % at low salinity of 100 ppt and the highest fat content was 35/81±1/64 % at salinity of 300 ppt. Also, the highest amount of carotenoids was produced 1/79 ± 0/30μg/mg under 300 ppt salinity stress in f/2 medium. The highest cell growth was 7808333±52041/6 cells/ml at 100 ppt salinity in Gillard culture medium. With increasing salinity of 300 ppt, the ash storage decreased by 7/18±76 %. In general, the results of this study showed that D. salina algae is a good source of pigments and fats when exposed to salinity stress.

The past studies have shown that the use of some probiotics has improved growth, reproductive and immune systems in crustaceans. Litopenaeus vannamei is the most important culture species of crustaceans in the country and this shrimp grows better than other shrimps. In this study, the effect of both probiotics based on quality indicators includes: larval stage index (LSI), larval condition index (LCI), larval dry weight, larval survival, Simultaneity of larval maturation to post larvae, time of emergence of first post larvae, duration of larval period and salinity and formalin stress tests in order to investigate Improvements in qualitative growth indices and immune system of Vanami shrimp larvae were examined. For this purpose, three concentrations of Bacillus probiotic with dose 6×105, 3×105 and 1×105 and three concentrations of Lactobacillus probiotic with dose 6×106, 3×106 and 1×106   were added to the water tank of Vanami shrimp larvae. The results showed that the larval quality indices at level 3 of both Bacillus and Lactobacillus probiotics were the best response and respectively, respectively 67±3.2 and 62±7.28, dry weight 139±3.99 and 138±22.23, larval stage index 11.55±0.26 and 11.46±0.11, larval condition index 1.86±0.06 and 1.88±0.13, Simultaneity of larval maturation to post larvae 1.45±0.23 and 1.41±0.04, time of emergence of first post larvae 7.5±1.1 and 7.7±1.52, duration of larval period 8.91±0.73 and 9.11±0.6 and salinity and formalin stress tests also show significant differences for all indicators except dry weight index and time of emergence of the first larval post for Bacillus probiotic. Finally, it can be concluded that the use of both probiotics increases growth, faster development, and longer survival and increases the resistance of the immune system.

Water quality management in culture ponds is the most important factor in the proper growth of shrimp and achieving proper production, which can help to improve the quality of the conditions of the pool floor and achieve the desired production. Poor quality water causes stress and illness. Today, ozone technology can be used in areas with viruses, bacteria, and fungi. Due to the high oxidation potential, ozone oxidizes the cellular components of the bacterial cell wall to reduce the number of inactive microorganisms. In this study, chronic ozone concentrations (0.02, 0.04, 0.06 mg/l) were applied serially to western white-leg shrimp for 60 days two hours after each diet. During the experiment, quality factors were measured, and at the end, growth factors and Body composition were performed. The results showed that salinity and temperature were in the optimal range of western white-leg shrimp and there was no significant difference between treatments (p>0.05). With increasing ozone concentration between treatments, dissolved oxygen, pH and nitrate increased and total ammonia, suspended solids, and nitrite decreased. Also, according to Body composition, there was a significant difference between the treatments in protein and ash levels with a decreasing trend and fat and moisture with an increasing trend concerning ozone concentration. The results of growth factors showed a significant difference between ozone levels, indicating the optimal level of growth factors in concentrations of 0.02 and 0.04, respectively.

TThis study examined the possibility of improving the quality of Macrbrachium rosenbergii larvae and water quality using different levels of Bacillus subtilis and Lactobacillus plantarum probiotics separately in semi-enclosed shrimp culture system. For the research conduction, 24000 newly hatched larvae of the giant freshwater shrimp obtained from the Ghasre-shirin hatchery center and were stocked in the experimental tanks by 40 larvae/liter density for one month. This experiment was designed in 25 liter tanks with four treatments; the first treatment (control without probiotic), the second treatment (106cfu/g), the third treatment (107cfu/g) and the fourth treatment (108cfu/g) in triplicates (for each of probiotics were designed separately). The results showed that with increasing the concentration of Bacillus subtilis probiotic up to 107 bacteria per gram, the parameters including DO, ORP, TDS, LSI and LCI have significantly an increase trend and at higher concentrations these parameters are reduced. It also showed that the bacterial density of Bacillus subtilis can be represented as a limiting factor and in higher concentration of 107 has negative results on larval growth and water quality. In L. plantarum probiotic treatment, increasing the number of bacteria, affected larvae quality and water quality, In the treatment of 108, the best probiotic performance of L. plantarum was recorded. In general, according to the results, the concentrations of 107 and 108 for B. subtilis and L. plantarum probiotics are respectively recommended in the hatchery centers of the giant freshwater shrimp.

Algae have the most important role in the production of fresh and marine aquatic animals especially at the stage of larvae culture due to their nutritional and also industrial components such as protein, unsaturated fatty acids, and pigments. Therefore, the researchers trying to improve the production of these micro-activated bio-cells with formulating the new media. This study, aims to investigate production of Nannochloropsis sp. (biomass production) under small scale and batch culture condition, using commercial agriculture fertilizers vs. and analytical grade salts for a period of 20 days. Five different culture media were formulated as treatments. Four concentrations (100, 75, 50 and 25%) of Cooper hydroponic culture media were tested and compared to F/2 medium that is commonly used for microalgae culture. Production of Nannochloropsis sp. Showed better results in 25% medium from eighth to twentieth days of experiment period. In the last day, cell production in treatment with 25% of copper formula (23.45×106±2.001×106 cell/ml) did not show any significant differences than F/2 medium (17.15×106±1.202×106 cell/ml) (P>0.05). The Medium 25% was also highly economic and capable for production of Nannochloropsis sp., since it showed almost 94% (sixteen times) cheaper than F/2 medium (excluding the cost of F/2 analytical grade vitamins) during formulation.

he aim of this study was to use a microbiome enriched with ammonia and nitrite oxidizing bacteria in the rainbow trout RAS system. A bacterial microbiome containing Nitrosomonas oligotropha and Nitrobacter winogradskyi (PAN) was added to a rainbow trout culture system (50 g) in the Aquatic Laboratory of the Fisheries Department of the University of Tehran and its effect on hematological parameters (hemoglobulin, hematocrit, erythrocytes, white blood cells, MCV, MCHC, lymphocytes, monocytes, and neutrophils) and stress (cortisol and glucose) as well as water quality of rainbow trout (Oncorhynchus mykiss) in a completely randomized design. In this experiment, a negative control (NC) group was also included for comparison with the experimental group. The results showed that by using PAN microbiome, the concentration of ammonia and nitrite produced was significantly reduced and as a result, this led to a reduction in stress and a reduction in immune suppression and improved growth. Therefore, the use of this bacterial group in improving the breeding system of rainbow trout is suggested by the rainbow trout breeding system.

In the present study, the effects of the different levels soybean meal replacement with sesame oil-cake in rainbow trout diet on growth performance, body biochemical composition and liver enzymes were evaluated. An 8-week feeding period were performed by Four experimental diets with different levels of sesame oil-cake 0% (S0), 5% (S5), 10% (S10) and 15% (S15), respectively, in a completely randomized design in triplicate. Growth and nutrition indices including final weight (FW), specific growth rate (SGR), weight gain (WG), feed conversion ratio (FCR), lipid efficiency rate (LER) and feed intake (FI) did not show significant differences between different treatments (p<0.05). However, there was a significant difference between S10 (0.23) and S15 (0.21) treatments in protein efficiency rate (PER). In contrast, hepato somatic index (HSI), visceral somatic index (VSI) and condition factor (CF), showed significant difference (p<0.05) between experimental treatments, so that most of them were related to the treatments (S10= 1.07), (S10= 6.29) and (S15= 1.05, respectively, and the lowest of them were observed in the treatments (S15= 0.98), (S15= 5.78) and (S0= 1.02), respectively. There was a significant difference in fillet protein, lipid and moisture (p<0.05) but the amount of ash did not show any significant difference. In addition, the activity of alanine amino transferase and aspartate amino transferase showed a significant decrease with increasing sesame meal and conversely, the activity level of alkaline phosphatase increased significantly with increasing replacement level (p<0.05). According to the results, it can be stated that not only the use of sesame meal instead of soybean meal up to 15% did not have a significant effect on rainbow trout growth and nutritional indices and also improved the health status and quality of the fillet biochemical composition.

Strengthen defense mechanisms with immune system stimulants like probiotics, it is a good way to prevent diseases and increase the efficiency of reproduction and breeding in fishers. Bacillus and Lactobacillus are a group of gram-positive bacteria and previous studies have shown that the use of these bacteria improves immunity and reproductive factors in aquaculture. In this study, the combined effects of optimal concentrations of two probiotics, Bacillus and Lactobacillus, on qualitative indicators including: larval stage index (LSI), larval condition index (LCI), larval dry weight, larval survival, Simultaneity of larval maturation to post larvae, time of emergence of first post larvae, duration of larval period and salinity and formalin stress tests in order to investigate Improvements in qualitative growth indices and immune system of Vannami shrimp larvae were examined. For this purpose, two concentrations of 3×105 (B1) and 6×105 (B2) CFU/g from of bacterial suspension mixtures Bacillus probiotic and two concentrations of 3×106 (L1) and 6×106 (L2) CFU/g from of bacterial suspension mixtures probiotic Lactobacillus in combination includes: B1L1, B1L2, B2L1 and B2L2 were added to the water of Vannami shrimp larval reservoirs. The results showed that the larval quality indices at different levels of combined probiotics differed significantly from the control treatment and the best results were at level 4, respectively: Survival was 61±3.41, dry weight was 143±5.48, larval maturation reached was 1.26±0.02, the time of emergence of the first larval post was 7.5±0.82, the length of the larval period was 8.4±0.15. The two indices of larval stage index and larval status index were examined on the third, sixth and ninth days. The results showed a significant difference between the control group and other combination treatments, and no significant difference between combination treatments for both indices. Salinity and formalin stress tests also showed significant differences between the control group with different levels of combined probiotics for all indicators. Finally, the most important quality indicators of larvae 31% increase in survival, 30% increase in dry weight, 33.8% improvement in the synchronization index of larvae reaching post-larvae, 14.7% decrease in the time of emergence of the first post-larvae and 20% reduction in larval duration was observed at level 4.

The aim of this study was to enrich the rotifer with microscopic algae as a feed in order to investigate their effects on growth indices and survival rates of rainbow trout larvae. For this purpose, Chlorella vulgaris and Scenedesmus quadricauda were used as foods, separately and together, for feeding the rotifer Brachionus plicatilis. In treatment 1, the larvae fed the enriched rotifers with chlorella, in treatment 2 fed the enriched rotifers with Scenedesmus algae and in treatment 3, fed the enriched rotifers with a combination of chlorella and Scenedesmus (50%). The control was performed using commercial feed. The density of algae cells per milliliter of water kept at 10 × 107 cells in each medium. In each experimental unite, a 60 liter of fish tank, 30 rainbow trout (Oncorhynchus mykiss) were stored. The mean (± SD) larvae weight reached to 409.66 ± 2.51 and 594.66 ± 4.93 mg on days 14 and 21 in the control group and the maximum weight was 694.33 ± 7.50 mg on day 21 in treatment 3. The specific growth, feed conversion ratio and protein efficiency and survival rates were also significantly different among treatments 1, 2 and 3 (P <0.05). The body composition analysis showed significant (P <0.05) differences in crude protein and crude fat indices in treatments 1 and 3 on day 21. The results of this experiment showed that the enriched rotifers with Chlorella and a combination of Chlorella and Scenedesmus could significantly improve the growth and survival indices in Larvae of Rain bow trout.

Balighli-chai and Ghare-Sou Dare Roud rivers are the main rivers of Ardabil Province in Iran which have had considerable alterations due to climatic changes and high-water withdrawals. The present study was planned to assess the water quality condition of these rivers based on the presence and abundance of the aquatic invertebrates macrofauna and Iran's water resources quality (IRWQISC) indices. The levels of abundance, Shannon-wiener index, Simpson's diversity index, FBI index, and IRWQISC were calculated in Fall 2018 for 18 stations along with the rivers. 12 families of aquatic macrofauna were identified in samples, with the highest abundance for Baetidae and Chironomidae and the lowest abundance for Asellidae. The levels of the Shannon-wiener index were between 0.4 and 0.6 for most of the sampling stations. The Simpson's diversity index had values between 0.3 and 0.6 for most of the sampling points. FBI index values for sampling points were in the fair to very good classes while the levels of IRWQISC showed relatively bad to bad conditions. Generally, the results indicated moderate water quality conditions for the studied rivers, which further revealed an urgent need for educated planning strategies to improve the ecological health conditions of these riverine ecosystems.

In this study with using plant proteins and yeast, several balanced protein diets were made with the aim of reducing the consumption of fish meal. Rainbow trout fingerlings (Oncorhynchus mykiss) to experimental diets and cultured in the aquaponics systems. The experimental treatments were control treatment (commercial diet), treatment 1(25% Fish meal (M)  and 57% (Plant protein) pp, treatment  (23%FM,4%yeast,47%pp) treatment3 (20%FM,9%yeast,52%pp) ,treatment4 (18/5%FM,14/5%yeast,46%pp),treatment5 (17%FM,21%yeast,41%pp), treatment6(10%FM,25%yeast,45%pp),treatment7(28/5%yeast,45%pp).The160 rainbow trout fingerlings with an average weight of 38 ± 2 and the 320 seedlings of peppermint (Mentha piperita) with an average weight of 25±2 gr were randomly introduced to the 16 experimental units and cultured for nine weeks. The results showed that the growth performance of fish such as final weight, specific growth and protein efficiency rates increased in treatment 3 compared to other treatments (P<0/05). Carcass composition showed that the highest amount of crude protein was observed in treatment 3, the highest fat crude was observed in control treatment, the highest moisture content was obtained in treatments 6 and 7. And there was no significant difference in ash content between treatments(P>0/05). The data from total bacterial count showed that the highest total count of bacteria in the intestine, reservoir water, and plant roots belonged to treatment 5, and the other treatments did not have any significantly differences. It seems that in these treatments, there were an equilibrium among bacteria of fish intestines, reservoir water, and plant roots. The best experimental diet in combination with rainbow trout and peppermint was recorded in treatment 3, and it was demonstrated that to grow rainbow trout using diets containing vegetable proteins, yeast, without using fish meal, is possible but to get the best growth conditions, it is needed to have at least 10% fish meal in the diet.

Leeches are very useful creatures, so they are used in the medical industry. The main problems of leeches breeding are high losses and water quality pollution. One of the effective ways to use water-improving probiotics is to improve water quality and reduce losses and increase survival and production. This study was performed using two new probiotics (HC, SA) in an experiment with 10 treatments in leech glass containers. The results show that the concentration of both probiotics used in 7.5 cc per liter in treatment 9 was more suitable than other treatments, so the possibility of using this concentration of probiotics in leeches breeding was actually able to grow more. Also, using quantitative strategic planning matrix coefficient, the main influential factors in leech breeding industry in leech breeding parameters in not using probiotics number 10 and in experimental parameters using commercial probiotics number 16 which is very practical.Finally, determining the future of leech breeding in Iran in order to meet domestic needs and exports and currency and competition in global markets is the use of new probiotic improvers that can be very important in increasing the survival and production of leeches.

The present study was conducted to evaluate the effects of nanosilver coating on the reduction of fouling fish cages of rainbow trout in the Ayush dam of Khorramabad from winter 2016 to autumn 2016. The nets were applied for antibacterial properties according to the exhaustion method The samples were collected from net panels (0.0625 m2) that were attached to the PVC frame, located at a depth of one meter from the side of the fish culture cages, and wet weight was measured, then it was identified with valid authentication keys. In this study, three genera of green algae and diatom were identified. The analyses showed that Do, temperature, and pH were positively and significantly correlated with Tetrasporaceae, wet weight and algae cover percentage. The Seasonal nanosilver panels treatment was free of fouling. Nanosilver coating can provide at least three months of effective protection against biofouling conditions. Nanosilver occupies the interstices of the polyamide polymer chain and interacts strongly with single pair electrons of nitrogen hence a coordinated complex is formed.

An experiment was conducted to determine the efficiency of two kinds of substrata (Polypropylene and cotton sheet), as biofilter media on removal of N-compounds and fish growth in a recirculating culture system for a 6-week period. Rates of survival was significantly different between treatments(p < 0.05). The mean (± SD) initial individual weight of fish was 3.4 ± 0.20 g and the fish attained to 9.19 ± 0.53 and 7.79 ± 0.38g in treatments with cotton sheet and polypropylene, respectively at the end of experimental period. Concentration of total nitrogen, total ammonia-N and nitrate were significantly different (p < 0.05) between treatments at the end of the experiment. Concentration of total ammonia-N reached to 0.050 ± 0.0021 and 0.054 ± 0.0039 mg L-1 in cotton sheet and propylene treatments, respectively. The electro-conductivities were significantly different and attained to 970± 0.32 and 900 ± 51.3µmos/cm in treatments with cotton sheet and propylene, respectively, at the end of experiment(p < 0.05). It was concluded that cotton sheet, can be used as an efficient bacterial substrate or medium in a recirculating carp culture system.