نشریه توسعه آبزی پروری
سال هجدهم شماره 1 (بهار 1403)

This study focuses on the interactive effects of biological substrate and diet protein reserve on the growth parameters and reproduction of white worm) Enchytraeus albidus). Two substrates including humus and loamy soil (a mix of %70 humus and %30peat moss) were used with three diets (with %20, %25 and %30 protein concentrations) followed by the use of 18 plastic boxes (30×20×15 cm) filled with 8cm depth of the afore mentioned soils. Upon preparing the substrate and the designated diets, a primary stock of 10 gram of the worms were released in each treatment. The worms were fed with the experimental diets for three months based on %60 of their biomass. Weight biometrics of worms in all treatments was conducted once during the course of study.  At the end, calculations were made on larval number, the number of larvae with generative cycle, brood stock increment rate, the number of larvae as per each brood stock, individual brood stock weight (mg), final biomass (in grams), ultimate brood stock number and the production cost of the diet per each kilogram of worm. The results showed interactive effects on certain growth and reproductive parameters among various substrates and the nutrition diets, revealing significant interactive effects on final biomass, brood stock increment rate, ultimate brood stock number, special coefficient No and diet production cost (p< 0.05). The brood stock with generative cycle showed a rising trend with the increase in diet protein reserve (p< 0.05). White worms in the mixed substrate had better growth performance than those of in humus with significantly higher larval number, brood stock with generative cycle, final larval weight and weight growth coefficient (p< 0.05).

This study was conducted with the aim of investigating the effect of alprazolam on sex steroids, ovarian tissue development and oocyte ultrastructure of three spot gourami after bromocriptine induction. A number of 90 adult female three spot gourami fish were purchased and divided into six groups of 15, including intact control group, solvent control group, bromocriptine control group, and three treatment groups receiving bromocriptine with a dose of 1 mg /kg and alprazolam with three doses of 1, 2, and 4 mg/kg. The drugs were injected intramuscularly in such a way that, control and treatment groups received bromocriptine in one day and the next day treatment groups received different doses of alprazolam. After completing the injections, the fish were euthanized and dissected. The ovaries of the fish were also removed to be examined by optical and electron microscopes. The tissue fluid was used to measure steroid hormones by ELISA kit. In the bromocriptine control group, steroid hormones had a sharp drop and the oocytes were in the peri-nucleolar stage. In treatment groups with bromocriptine and alprazolam at a dose of 4 mg/kg, the levels of 17β-estradiol and testosterone was higher than all control and treatment groups (p<0.01) and oocytes were in vitellogenin stage. Therefore, a high dose of Alprazolam was the stimulant of gonadal development and oocyte growth in three spot gourami fish. it can be concluded that bromocriptine blocked the HPG axis and alprazolam caused re-stimulation of this axis, oocyte maturation and ovarian sex steroid secretion.

The use of dietary supplements plays an essential role in enhancing fish consumer safety. On the other hand, the presence of nanoparticles affects the physiological status of fish and decreases their immune function. Therefore, the use of safety stimuli such as molasses may be necessary. The present study was performed to assess the hematological indices of molasses-fed common carp (Cyprinus carpio) exposed to titanium nanoparticles. Accordingly, 250 fish with a mean weight of 20±0.62 g was divided and fed for 42 days in four treatments, diet without molasses (treatment 1), diet containing 0.5% molasses (treatment 2), 1% molasses (treatment 3) and 2% molasses (treatment 4). At the end of the feeding period, each group received 50% lethal concentration of nano-titanium for 14 days. Blood samples were taken to measure blood levels at the end of the experiment. The results of the present study showed that with increasing molasses diet, the number of white blood cells significantly increased and also in the molasses treatments exposed to nano-titanium, there was also a significant increase in the number of white blood cells. Red blood cells, hematocrit and hemoglobin increased in molasses-fed diets and this trend was increased with increasing molasses concentration in diets and was significantly different from control group (p<0.05). The conclusion of this study showed that blood monocyte levels decreased in nano-titanium and molasses combination treatments. So, molasses in combination with nano-titanium has been able to improve undesirable lesions. Also, the number of blood lymphocytes in nano-titanium and molasses combination treatments increased, which means molasses in combination with nano-titanium could improve the reduction effect of nano-titanium.

In order to evaluate the possibility of common carp culture, Cyprinus carpio, in cages located in the Caspian Sea, 700 common carp with an average weight of 50±10 gr were introduced in two floating cages (each cage contains 350 fish) in Anzali Free Zone. The fish were fed daily based on the fish biomass on two occasions using extruded pellet food. After 2 months of introduction of fry, the loss of 2-3 fish per day started. The biometrics also showed that the fish just reached to average weight 85.64±12.07 and do not grow properly. In order to identify the reasons for the lack of proper growth and gradual death of fish, sampling was done to investigate the bacterial pathogens and the pathological condition of the gill tissue. By bacterial tests Aeromonas hydrophila from internal organs including liver and spleen and Pseudomonas sp. was isolated from the gills of investigated fish. The pathological examination of gill tissue also showed extensive histopathological effects such as bleeding, hyperplasia of the epithelium, twisting and adhesion of the secondary blades, destruction of the pillar apparatus and gill chloride cells, etc. Probably, some of these injuries are the result of infection with bacteria and others are the result of environmental conditions, especially the relatively high salinity of seawater. At the end of four months of rearing, the fish survival rate was about 30% and the average final weight was 350 ± 150 gr. In general, the biological characteristics of common carp showed that although this fish is able to tolerate salinity to some extent and sometimes can be seen in the composition of sea catch, it is basically considered a freshwater fish and its cultivation in floating cages in the Caspian Sea where salinity varies between 7-13 ppt is not reasonable and economic and it is not recommended.

The development of aquaculture is inevitable with increasing population and to ensure food security. On the other hand, due to the limitation of fresh water, the development of aquaculture is expanding in the sea. In the last decade, the rearing of Rainbow trout (Oncorhynchus mykiss) in Caspian Sea cages was done to form a production chain with pond farms to produce big-sized fish for export. The purpose of this research was the economic evaluation of the production of big-sized (1.5< kg) Rainbow trout in sea cages using the Cost-Benefit Analysis (CBA) method. This research was done in 4 sea farms in the south of the Caspian Sea. Fish with an initial weight of 500 grams were introduced into the floating cage (volume of 2500 cubic meters). The fish reached a weight of 1517±71 grams to 1799±178 grams in 90 days of the rearing period. All production costs (variable and fixed costs) and profit from fish sales were calculated. For the economic evaluation, each marine farm was considered with four floating cages and the production rate of 5, 10, 15, 20, and 30 tons of fish for each cage. The results showed that the minimum reasonable profit margin for a farm with a production of 80 and 120 tons of fish and taking into account a loan with a bank interest of 23% and a 10-year equipment depreciation period has 30% and 70% net profit, respectively. On the other hand, raising rainbow trout in floating cages with a volume of 2500 cubic meters and producing less than 20 tons (less than 8 kg per cubic meter) for each cage is not recommended in marine farms in the southern Caspian Sea region.

Iran's aquaculture industry has experienced significant growth in the last two decades, among which rainbow trout as the essential cold-water breeding species has particular importance and a high production growth rate. Of course, this rapid increase in production has created problems and risks for this activity, which need better and principled management to solve them. Among the management factors that are ignored is the issue of transporting fish and eggs. Fish transportation activities, such as moving, trapping, and exposing to optimal water quality, can cause physiological changes in fish due to increased stress. In addition, understanding misplaced environmental conditions and how they affect fish often leads to new protocols that reduce stress and the risk of disease transmission. Among the principles of fish transport discussed in this study is the regulation of osmotic pressure, dissolved oxygen, suspended solids, ammonia, the temperature of the transport tank and its preservation, carbon dioxide, physical fishing, and drugs and Anesthesia noted. The stages of ocular egg transfer are also examined separately. Considering the importance of quarantine and its essential role in preventing the spread of infectious diseases, we have also examined its basic requirements and implementation levels.

Considering the effect of plant immunostimulants on non-specific immune response in aquatic animals, the present study was conducted to investigate the effects of supplementation of goldfish (Carasius auratus) diet with (Utrica dioica) hydroalcohalic extract on mucosal immune response (total immunoglobin, lysozyme and protease) as well as immune related (TNF-alfa) gene expression. For this purpose, 180 fish with an average weight of 0.192 ± 0.014 were randomly divided in 6 aquaria (two replicate) and fed with this extract on three levels: 0, 2 and 4 gr/kg. Evaluation of mucosal immune parameters revealed that supplementation of diet with Utrica dioica significantly elevated lyzozyme and protease activity in fish fed 4 gr/kg compared to control and 2 gr/kg (p<0.05). Total immunogloubin didn’t show significant difference in fish fed supplemented diet compared to control (p>0.05). Molecular studies on immune gene (TNF-alfa) gene expression revealed significant increase in Achilleamille folium fed diet (p<0.05). Results showed immunomodulatory effects of dietary Utrica dioica extract on skin mocus as well as expression of inflammatory cytokine in gold fish.

In this study, the biochemical parameters of Artemia franciscana fed with Isochrysis galbana and Tetraselmis suecica microalgae cultured with different carbohydrate sources were investigated. Glucose, sucrose and fructose were used as different carbon sources. Artemia was cultured under standard conditions in 24 circular polyethylene tanks (8 treatments and three replications) with a volume of 300 liters and a density of 1000 nauplii per liter of water. The breeding period was 30 days. The results showed that there was a significant difference between different treatments of cultured microalgae with different carbohydrate sources in terms of biochemical parameters (p<0.05), and between treatments of tetraslimas microalgae cultured with sucrose in terms of protein, fat, Ash and carbohydrates showed significant differences with other treatments (p<0.05). In Isochrysis microalgae, sources of sucrose and fructose caused the highest amount of protein (p<0.05). Analysis of biochemical values in Artemia fed with two groups of microalgae showed that there is a significant difference between different treatments (p<0.05); Among the treatments, Artemia fed with Tetraselmis microalgae and Isochrysis cultured with sucrose showed a better condition than other treatments. Therefore, it can be concluded that the values of biochemical parameters of Artemia fed are related in the first place to the type of algae and in the second stage to the nutritional source of algae. Therefore, the use of both studied algae species grown in different carbohydrate sources can increase the nutritional value of Artemia; But in general, the treatment of Tetraselmis containing sucrose has the highest nutritional value compared to other treatments in Artemia.