نشریه آبزیان زینتی
سال نهم شماره 3 (پاییز 1401)

This study was performed to evaluate the effect of feeding with Oregano Vulgare essential oil supplementation on the brain tissue of Koi fish under long-term exposure to naproxen. For this purpose, 135 Koi fish (Mean weight: 1.5 gr; Average length: 6±1 cm) were divided into three groups with three replications. These fish were fed with two diets including a basic diet (BD) and an essential oil diet (OED) for 30 days. They were then exposed to naproxen (NP) for 14 days. Treatments included a control group (C): BD feeding, T1 group: BD feeding and NP toxicity, and T2 group: OED feeding and NP toxicity. Brain tissue sampling was performed at the end of the experiment. Tissue samples were examined after fixation in Bowen's solution and preparation of histopathological slides. The most common complications in T1 treatment were gliosis, vacuolation, necrosis, inflammation, and hyperemia. These complications were observed in T2 with a less destructive effect than in T1. These results showed the positive effect of feeding with oregano essential oil in reducing tissue damage exposed to NP toxicity in Koi fish. Due to the widespread use of NP and the persistence of this drug in the surface waters of the world, it is important to investigate the effects of this drug contaminant on non-target organisms. Therefore, it is necessary to identify and introduce practical strategies to reduce the adverse effects and economic losses of toxicities with these pollutants.

The aim of this study was to compare the effects of feeding two different diets on the growth rate and survival of zebrafish in order to produce resistant and better-quality fish. For this purpose, two experimental diets with different levels of protein and fat were given to zebrafish (20 days old) five times a day for a period of 70 days (10 weeks). The results of this research showed that feeding with two rations with different levels of protein and fat on the indicators of length growth, weight growth has created a statistically significant difference among the treatments (P<0.05). Loss rate (survival), food conversion ratio, daily growth percentage and weight gain percentage are also highly significant (P<0.05). In total, fish fed with a diet with protein levels of 51.5% and 11.5% fat had better growth and survival rates than fish fed with protein levels of 40.2% and 7.7% fat. This proves that zebrafish has a high ability to use fat as an energy source. The use of appropriate levels of non-protein energy sources in the diet of this fish can reduce protein catabolism in order to produce energy, as a result, we will see an increase in the growth rate of length and weight in this fish.

Ornamental aquaculture is a leading and profitable industry in Iran. One of the essential needs for the development of this industry is the introduction of popular species. Therefore, it is necessary for experts and breeders of ornamental aquatics to introduce important ornamental species around the world and provide their ecological and biological characteristics, and reproduction techniques. To achieve this goal, the present study was conducted to review the biological and ecological characteristics of one of the most popular ornamental fish species in the world, Bluefin Notho (Nothobranchius rachovii). According to the literature review, the Bluefin Notho is a peaceful species of the family Cyprinodontidae, which was first described in 1926 from Beira, Mozambique. The distribution range of this species in Africa includes temporary ponds and swamps or pits full of water that are exposed to drying annually. This species often prefers habitats with muddy beds and minimal minerals. It lives in habitats that have muddy beds with acidic water and minimal minerals. As the water level decreases, the Bluefin Notho lays its eggs inside the mud and preserves them until the water level returns to its previous state. These fish can withstand harsh conditions in their natural habitat and can spawn and hatch in wet seasons. The presented data can be used to develop the aquaculture industry in the freshwater aquarium fish sector especially in the breeding and maintenance of Bluefin Notho.

Infusoria are a group of aquatic organisms that are used to feed fish larvae. They are actually small forms of life in freshwater that include: Amoeba, Oglena, Green algae, Paramecium, Rotifer, Vertisella, and Invertebrates are small. Due to its small size, Infusoria can be used to breed newly hatched larvae of many aquarium fish species such as gourami and beta fish. Many home aquarium owners are naturally unable to provide enough infusoria to raise fish larvae. Infusoria can be grown by soaking any decomposing vegetative material such as lettuce and cabbage in an old, chlorinated, glassless water bottle. Depending on the temperature and light received, the infusoria begin to multiply within two to three days after planting. The water is initially cloudy due to the increase in the level of bacteria, but when the infusoria consume them, the water becomes clear. At this stage, infusoria are usually visible to the naked eye as small, white moving spots.

Koi is one of the ornamental fish that lives in freshwater streams, lakes and lagoons. Geographical evolutionists believe that its origins from central Asia and Iran. The Koi Fish are benthivore. It was famous in the name of Magoi in the Old Persian Empire. The Japan and China have imported this fish from Persian Empire and started to cultivate them many years ago. The red and white koi fish are very popular. Propagation in many diversities of this fish in different colors is very popular in the rest World.   Koi culture shows success in hatching rate in industrial methods. Producing fish larvae are very important in these industrial methods.  Koi farmers prefer traditional methods due to existence of many stress factors in Koi intensive industrial culture. Non intensive and semi-intensive methods are very popular among the Koi fish farmers.

The rapid development of fish farming and the increasing demand for fish have led to the dense cultivation of fish, which in turn has caused stressors for fish and thus increased the risk of disease. until now, the use of chemicals has been widely used for prevention and treatment, however, the use of chemical drugs has several negative effects on the environment (creation of resistant strains of bacteria) and human health (accumulation in tissues). medicinal plant compounds are readily available, especially for small-scale fish farmers, they are easy to use, nature friendly and degradable. since there has been a lot of attention recently to the use of plant compounds as a substitute for chemical hormones, therefore, in this article, the use of medicinal plants in sex reassignment, reproduction and breeding of different species of fish is mentioned. in this study, the library method has been used.