نشریه توسعه آبزی پروری
سال چهاردهم شماره 4 (زمستان 1399)

The present study aimed to determine the effects of iron nanoparticles (Fe-NPS) on growth performance, survival rate, liver histopathology and some blood and immune parameters of stellate sturgeon (Acipenser stellatus) juvenile. A total of 144 fish (175-195 g) were fed diets containing graded levels of Fe-NPs (0, 25, 50 and 100 mg kg -1 diet) for 8 weeks. Based on results, no significant differences were observed in body weight increases, specific growth rate (SGR), feed conversion ratio (FCR), mean cell volume (MCV), mean cell hemoglobin (MCH), mean cell hemoglobin concentration (MCHC), eosinophils, monocytes, albumin, alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lysozyme activity between treatments (P>0.05). Fish fed 50 mg Kg -1 Fe-NPs showed a significant difference in the red and white blood cells, neutrophils, total protein, respiratory burst activity, and total immunoglobulin level (P<0.05) with no negative effect on the fish liver. After 8 weeks, survival rates of 86.11%, 94.4%, and 97.22% were recorded in groups that received 25, 50 and 100 mg Kg -1 Fe-NPS, respectively. Survival rate in control group was 94.44%. These results indicated that Fe-NPS at level 50 mg Kg -1 improved the welfare and survival rate of stellate sturgeon juvenile and had no negative effect on the fish liver.

Today, use of medicinal plants is important for control of the disease-causing agents, including parasites, rather than chemicals. This study was conducted to evaluate the efficacy and effective dose of Zataria multiflora hydroalcoholic extract in the fight against external protozoan parasite (Trichodina). For this purpose, after determination of the lethal concentrations (LC50) of this extract on Persian sturgeon, a study was conducted to determine the effective dose (EC50). In this study, the effects of Zataria multiflora extract on white blood cells were also investigated. The results of differential white blood cells count in studies of EC50 extracts showed statistically significant differences in the level of lymphocyte, neutrophil and eosionophil in different treatments (P>0.05). The effective concentration of Zataria multiflora hydroalcoholic extract on Trichodina sp. was determined in the concentration range of 200 to 600 mg/l and this effective dose was calculated as 437.6 mg/l for one hour of bath time. This dose was classified in the category of substances with low toxicity and substitution Suitable chemicals. Therefore, this extract is recommended to remove Trichodina parasite in sturgeon fish farms.

In this study, tissue changes of the sex organs in the Tinca tinca fish in Anzali wetland and breeding conditions was compared. 96 fish were collected from the cultivating pool and 36 others from Anzali wetland. In the microscopic study of Tench and ovaries and testicles in different stages of sexual activity, from the samples of the wetland, from 3 fish of ovary, two of them were in stage III- IV and one was in stage III (colder water). Furthermore, in the samples, of 8 samples taken, 7 were in mature stage, and one was in stages III-IV (in warmer conditions). In late April, when the water temperature increased to 19°C, tissue from ovaries of fish contained follicles after foliar application (oocytes with accumulation of yolks and open oocytes). In the largest oocyte, the vacuoles were near the nucleus. The study on 24 fish species of stage 4 and 5 with weight from 50.9 to 228.2 gr and mean 99.86 ± 41.17 grams and a total length of 146 to 233 with a mean of 176.93 ± 22.28 mm and age equivalent to 3 to 6 with a mean of 4.00 ± 0.93 years. The absolute density ranged from 14086 to 153600 with a mean of 36362 ± 28208.77 and a relative density of 170.1 to 644.8, with an average of 367/9±125/02 pounds per gram of fish. The results are as follows: The testis of this fish is lobular and spermatogenesis in fish coincides with sperm shedding or absorption begins in the spawning season and gradually progresses to mid-autumn.By increase of temperature, the reproduction and sexual properties of male and female of Tench was significantly increased. The highest mean diameter of eggs was observed in May and the lowest in August. The peak of sexual maturation in female fish was in March and April. Spawning of fish began in May and continued until late July. Oogenesis and spermatogenesis in breeding environments start earlier than Anzali wetland.

In this study, the effect of the color of the bedding of cultivating aquariums (white, black, green, blue) on growth performance, nutrition and biochemical composition of the body of large freshwater shrimp (Macrobrachium rosenbergii) post larvae was investigated. All laboratory and experimental stages of this study were carried out in the fall of 1397 and for 60 days in an ornamental fish plant located at the Faculty of Natural Resources, University of Guilan. At the end of the experiment, the growth and nutrition indices (weight gain, weight gain, specific growth rate, survival percentage, feed conversion ratio, dietary efficiency, protein efficiency ratio, status index, body length increase) and biochemical parameters of the body were measured. According to the results, the best growth and nutrition indices were observed in treatment 2, 3, 4 and 1, respectively. Body moisture content showed significant differences among treatments, and the highest and lowest levels were observed in treatment 1 and treatment 4 respectively. The percentage of protein and body fat in treatments 1 and 4 did not have any significant difference and the lowest values ​​were allocated. The percentage of protein and body fat in treatment 2 and then in treatment 3 were significantly higher. Also, the highest percentage of body ash was observed in treatment 2. Finally, it can be said that the color of the background of cultivated aquariums, especially dark colors such as black and blue, can have a positive effect on aquatic species.

The use of selected bacteria to improve growth parameters and the microbial population in the host is one of the new ideas carried out for manipulating the bacterial population in aquatic organisms. These bacteria also consumed in the diets of farmed fish to optimize the balance of the microbial population of the gastrointestinal tract and they have a great effect on the growth and survival provides them. This study aimed to investigate the effect of commercial aquaculture probiotic (CA probiotic, Superzist, Zistyar Varna, Iran) on the growth performance and survival of juvenile of Siberian sturgeon. A number of 120 of Acipenser baerii with average of weight (109.3±3.7 g) were randomly distributed to 12 fiberglass tank containing 350-liter fresh water and 10 fish per tank. Fish were fed 2-3% body weight three times daily for 63 days. The CA probiotic comprising Bacillus subtilis, Lactobacillus acidophilus, L. delbrueckii, L. rhamnosus, L. plantarum in amount of 100, 200 and 300 mg/kg were added to basal diet (4mm pellets, Skretting, Italy). At the end of experiment, the survival rate of fish in the treatments were 100% and there were no significant difference in the treatments (P>0.05). There were no change in SGR in the treatments. Biomass increase, WG and BWI were increased and FCR and PER were decreased by increasing the amount of CA probiotic in the diet but there were no significant (P>0.05).

Cu is an essential micronutrient which is found in either water environment or fish diet. In addition, copper sulfate is an effective algaecide for algal control in fish pond. Therefore, toxicity test seems to be necessary to predict the safe concentrations of chemicals in the environment. The experiments were conducted to study of mortality rate of acute toxicity of Copper (CuSO4) in Common Carp (Cyprinus carpio) and Caspian kutum (Rutilus caspicus) fry.13 fishes with average weight of 2±0.5 and 20±2.2g to R. caspicus and C. carpio  respectively were exposed to different concentrations of copper salt respectively. The experiments were done by Static Method during 96 hours. In the experiments, the different concentrations of copper such as 0, 0.1, and 0.2, 0.3, 0.4, 0.45 and 5mgL-1 were used. Under stable condition (T= 25±1OC, pH=7.8 ± 0.2), the lethal concentration of copper (LC50) was measured of 0.4mgL-1 and 0.45mgL-1 to R. caspicus and C. carpio respectively during of 96 hours. There were significant differences between treatments with each other and also with the control (P<0.05). So, with increasing of copper in each treatment, the mortality rate of fish significantly was increased. For studying histopathological, 3 fish were selected randomly from each treatment and after killing fish, samples of liver, kidney, and gill tissue were taken from each fish. These samples (sections) were stained with Hematoxylin-Eosin and then the impacts of Cu on the fish organs were studied under light microscope. Histopathological findings showed that major lesions were hemorrhage, hyperemia, hyperplasia and epithelial cells necrosis, degenerated tubules of their kidney, expansion of Bowmanchr('39')s capsule and hepatocytes necrosis in 0.3, 0.4 and 0.45 concentrations respectively. There were any lesions in control.

Contamination of Saprolegnia sp. fungi in edible and ornamental fish is one of the common problems of fish aquaculture ponds and aquariums and has economic losses. The aqueous, methanolic, and hydroalcoholic extracts of Spartium junceum and Melissa officinalis were prepared by maceration and condensed by rotary. Four concentrations of 20, 30, 40 and 50 mg/ml of the extracts were used. The fungus was isolated from fins of the infected fish and cultivated in sabouraud dextrose agar medium. For the effectiveness of extracts, the agar well method was used. GraphPad Prism, software and Anova and Tukey tests were used. At a concentration of 50 mg/ml the M. officinalis aqueous extract with a mean halo of lack of microbial growth of 20.8 ± 1.06mm had the highest inhibitory effect on growth, followed by a hydroalcoholic extract with halo of lack of microbial growth of 17.73± 1.1mm, and then the methanolic extract of S. junceum had the mean halo of lack of microbial growth 15.4 ± 2.12 mm. The Nystatin antibiotic did not produce any halo of lack of microbial growth. Using plant extracts instead of antibiotics and malachite green could be a good alternative. Particularly, aqueous extract of M. officinalis is recommended because it has the greatest effect and is also beneficial to the health of fish and humans.

Regarding climate change, it is important to determine the most suitable time for starting its cultivation on the site of Gomishan shrimp. For this purpose, in range of air temperature (15-25°C), 21°C was chosen as the base temperature for Gomishan area. This experiment was conducted in 8 terrestrial ponds that were different of density (350000, 182000, 100000 ind/he and time of stocking; 18 Jun, 27 Jun, 4 Jul, 22 Jul) in 2012. Physico-chemical parameters and biometric data were two-weekly taken. The results showed that some of the parameters including pH, transparency, ammonia, nitrate, calcium, and potassium ions were sometimes out of the suitable range. The lowest final weight was 12.68 gr. in a pool with a density of 350,000 ind/he and the release time of June 28th with 127 days of breeding and the highest was 16.07 grams of the 100000 ind/he, it’s of June 19th during 128 days. The highest SGR% was observed in the pond stocking 182000 ind/he in early June. It seems, May 13th to May 23th are suitable time for starting shrimp cultivation on the site of Gomishan with higher density but it delay in starting cultivation, it is better lower density with larger postlarvae for reach to suitable weight.

Rainbow trout is one of the 100 exotic invasive species in the world, and the biological characteristics of evaporated specimens of marine cages on the coast of Mazandaran including sex ratio, length and weight relationship, and growth are necessary. In order to study the rainbow trout growth parameters, 90 specimens of this species were collected from October 2017 to May 2019 from catching bony fish from west to central coast of Mazandaran, in order to study the male sex ratio was 1.04 and was approximately equal. The mean length and weight of fish caught were 31.82 ± 1.03 cm and 566.05 ± 44.02 grams, respectively. The caught specimens consisted of 4 age groups 1+ to 4+ and the 1+ group was the highest, accounting for more than 35.6% of the specimens. The growth pattern of this species allometric negative was W= 0.038*L2.7. In different sexes, allometric was negative, so that the length and weight relationship was obtained in the female sex W=0.07*L2.6 and in the male male W=0.11*L2.4. The maximum estimated length (L∞) for this species was 68.98 cm and its other growth parameters in the Van Bertalanffy equation Lt = 78/68 {1-EXP[- 0/67 (t + 0/05)]}. The results of this study showed that this species does not grow well in the Caspian Sea and the most frequent is the age group under one year old. Fish escape from cages in different years has occurred and the possibility of initial life and compatibility with the Caspian Sea ecosystem for this exotic species with its environmental conditions is provided in terms of salinity, temperature and nutrition.

This study was carried with aim to investigate the restriction of feed, compensatory growth and the effect of probiotic (Bacilact) on growth performance, food productivity, survival and carcass composition of rainbow trout. Experiment was performed using a completely randomized design with three treatments consist of without hungry and basilicate treatment, feed restriction treatments with and without Bacilact during 2 weeks. The treatments were fed in re-feeding phase, to satiety for 4 weeks. The number150 of rainbow trout larva were fed with an average weight of 21.20 ± 1.31 g with the experimental treatments during 42 days breeding period. The results showed that the effect of treatments on weight and length growth, feed conversion ratio, daily growth ratio, specific growth ratio, survival rate, condition factor and survival rate were significant (P<0.05). Also, the effect of treatments on FER, PER, protein and fat percent carcass was significant (P<0.05). The diet containing probiotic with Bacilact compared to without Bacilact group improved the survival rate of rainbow trout. Regarding the higher SGR, the results showed that compensatory growth process in fish with 2 weeks of starvation and re-feeding with Bacilact is more than re-feeding without Bacilact. In conclusion, this study showed that probiotic (Bacilact) had a positive effect on growth and nutritional factors as well carcass composition in comparison to re-feeding without Bacilact in rainbow trout.