نشریه ماهیان دریایی
سال پنجم شماره 2 (پیاپی 7، پاییز و زمستان 1400)

Amyloodinium ocellatum parasite is the most important and common dinoflagellate parasite of fish. This ectoparasite penetrates the skin and gills, can caused to serious damage and suffocation or non-osmoregulation, in marine fishes. It also tolerate salinity and water temperature changes well and, due to its nonspecfic in host, quickly infects lot of brackish and saltwater and aquarium fishes. In this research deals with the mortality of gray mullet juveniles caused by the Amyloodinium parasite, which are cultured in the aquaculture workshop of the Offshore Fisheries Research Center for breeding. For investigate the cause to mortality, Amyloodinium ocellatum parasite was observed by light microscopy and wet smear from skin and gills. As soon as decrease of water temperature, which coincides with October in autumn, the conditions are provided for the occurrence of this parasite. The parasite was removed with a long-term bath of fresh water and formalin 200 ppm for 45 minutes and a short-term bath of copper sulfate 5 mg/l for 15 minutes daily after 5 to 7 days. However, inlet water disinfection and exchange tanks are necessary to remove tomonts.

One of the important potentials in the country is the existence of unconventional water, which is considered as an environmental challenge in the country. Due to the lack of acceptance of these water resources by agriculture, the aquaculture industry can reduce the pressure on fresh water resources and also The production of aquaculture products can take a step in this direction. In this regard, sea bass (Asian sea bass) culture in unconventional waters was done in two pilots (cage and earthen pond). Feeding and growth indices were examined during the period. Initial weight in the cage was 23 g. The maximum culture period was 90 days. In the earthen pond, the initial weight was 56 g and the duration of the period was 130 days. The results showed that growth and feeding indices have a good trend during the culture period. Studies of water, sanitation, heavy metals and toxins in fish and water showed that culture in these water resources is standard limit in terms of human consumption. Due to the potential of fish culture in sugar cane drainage, it is possible to create jobs and produce aquatic animals by observing aquaculture standards. Providing the good food, fingerling with the appropriate size and price can help increase productivity.

Today, cage aquaculture in the open sea is a new approach and is one of the most important reasons for the success of communities in the aquaculture industry. This approach provides the basis for increasing production capacity due to the vastness of the seas and, due to the lack of need for aeration, reduces the costs of supply and maintenance and, consequently, suitable breeding conditions. In order to achieve the above goals, it is necessary to focus more on the technical aspects in order to pave the way for the development and commercialization of this technology. In this research, scientific points and findings in the design and implementation of cage structures have been presented. These tips include the basics of site selection, building materials, and finally estimating the size and number of cages.Examining the experimental data samples, the relationship between cage net size, biomass weight, and fish weight was presented. The results also showed that with increasing the cultivated area, the number of required cages has almost linear growth, so that with 5 times the area, the number of required cages will increase by a factor of 1.2. Regarding the material of cages, the results indicate that the material of cages suitable for breeding in the Caspian Sea and Persian Gulf waters is polyethylene, but the volume of cages in the Caspian Sea is about 2.25 times larger than the waters of the Persian Gulf. Is

One of the key problems in the lack of development of the marine fish industry in the world is the failure to produce juvenile fish continuously in captivity. This is due to the high mortality of marine fish larvae during rearing in captive conditions. The high mortality of larvae at this stage can stem from various factors. Specifically, nutrition is one of the central factors in the success of aquaculture activities and has a direct effect on reducing or increasing mortality during the larval period. In spite of significant advances in fish nutrition, many questions remain unanswered regarding marine fish larvae nutrition. Marine fish larvae lack a stomach in the first weeks after hatching. However, this does not mean that the digestive tract is non-functional, but the challenge is to determine which nutrients, molecules, or particles the gut can be digested and absorbed. A comprehensive understanding of the nutritional requirements of marine fish larvae contributes to the development and fabrication of formulated feeds and the utilization of essential nutrients to enrich live foods during larval rearing in captivity. This subject leads to increased growth and survival of larvae.

Selenium is a non-metallic element and a kind of essential micronutrient for the body, which has chemical properties similar to oxygen and sulfur. Due to its unique physical, chemical and biological characteristics, it plays an important role in the ecosystem cycle of running and sea waters. Selenium is one of the low-requirement substances for animals, which as a cofactor in the structure of glutathione peroxidase enzyme plays an essential role in inhibiting the destructive effects of free radicals in the body and is vitally important in the antioxidant defense system, thyroid hormones and insulin function, regulation It has cell growth and fertility maintenance. Today, selenium-containing diets have received much attention in the feeding of aquatic animals. It is important to use the appropriate selenium supplement in the diet to improve the performance of aquatic growth and physiological and biochemical functions in fish. Selenium is used in inorganic, organic and nano forms in fish feed, but the use of inorganic selenium in fish food formula has been more than other forms.