نشریه آبزیان زینتی
سال هشتم شماره 3 (پاییز 1400)

The aim of this study was to review the biological and ecological characteristics of kuhli loach (Pangio kuhlii). A review of the sources revealed that this species has an eel-shaped and elongated body and four pairs of barbels. In this fish species, the fins are very small, the dorsal fin starts in the middle of the body and the anterior fin is behind it. At the time of maturation, kuhli loach reaches about 7 cm and its maximum length reaches 10 cm. This species is usually found in shallow areas or other quiet habitats such as swamps and reservoirs behind dams. The natural habitat of P. kuhlii is sandy beds in slow-moving rivers. The species is native to Sumatra, Borneo, Java and Malaysia, and its distribution areas are recorded in Asia and the Americas. Pangio kuhlii is known as an active cleaner and is ideally suited for the aquarium industry. This study has provided the basic requirements for the maintenance of kuhli loach for use in the ornamental aquatic industry.

The aim of this study was to investigate the possibility of isolating study stocks of spirlin populations (Alburnoides eichwaldii) using morphometric traits in rivers of Golestan province, between three regions of Zarrin Gol, Mobarakabad and Dasht in spring 2016. For this purpose, first 45 samples of tailoring fish were caught, then Morphological traits were measured using a caliper with an accuracy of 0.01 mm. In morphological traits, the possibility of separating the two reserves was studied from the principal component analysis method. The present study showed that the samples were separated in three areas, which could be due to habitat conditions and bed material. In general, similar studies for rational and efficient management of fisheries and protection of biological resources and genetic resources, identification of storage structure a species of fish native to each region is recommended.

Controlling ornamental fish disease has a key role in reducing treatment costs and improving growth and health status. Disinfectant solutions such as formalin (F) and methylene blue (MB) are some of the effective disinfectants in the aquaculture industry. In this study the effects of simultaneous exposure to F-MB on some haematological and plasma cortisol and glucose levels on ornamental catfish, Pangasius hypophthalmus were analyzed. 60 fish, average body weight 83.2±12.67 g, were randomly chosen and put in two groups, control and F-MB, in 6 separate glass tanks (each 10 fish). The fish in the F-MB groups were exposed to formalin, 5 ppm and methylene blue, 4 ppm for 72 hours. After exposing time, blood was taken from the caudal vein and some haematological parameters plus plasma glucose and cortisol levels were analyzed. The results showed that exposing fish to F-MB disinfectant could not cause any significant changes in preliminary and secondary haematological parameters in fish (P>0.05). Even though, fish in F-MB groups showed higher plasma levels of cortisol and glucose as tension indicators in comparison to the control fish (P<0.05). It could be concluded that although simultaneous exposure to F-MB could not affect haematological parameters of ornamental catfish, it had some negative effects on tension response and need to use under exact stewardship. Study on the other fish welfare parameters as well as exposure to other disinfectants can help us to select the best option under culture condition.

The present study was conducted to review the biological, systematic, distribution and conservation features of the midget dwarfgoby, Trimmatom nanus as one of the smallest fish in the world. Studies have shown that this marine goby is native to the Indian Ocean and the western Pacific. Midget dwarfgoby was described in 1981 from the Chagos Archipelago, the center of the Indian Ocean. Distinctive features of this species are having a semi-transparent body and slightly orange-colored. This species has a standard length of 8-10 mm in adult females. The midget dwarfgoby inhabits mostly in deep coral reefs at depths of 5-35 m. This fish species is considered in the IUCN Read List as a species with Least Concern (LC).

A parasite is a protozoan of the Holotrich ocular family. It is a mandatory parasite of freshwater fish and is a known cause of white spot disease in fish. The disease is highly contagious and can be transmitted from one fish to another without the need for direct interface hosts. Although one is often thought of as the pathogen of warm-water fish, its onset usually occurs when the water temperature is changing, especially in the spring when the water temperature is rising. The classic sign of infection is the presence of small white spots on the surface of the skin and fins of fish. These spots, which are actually adult parasites, penetrate the outer surface of the fishchr('39')s body and create a space in the surface layers of the body for feeding and movement to the surrounding areas, which can cause heavy losses if not treated in time. Therefore, it is very important to know it. The aim of this study was to evaluate, identify, prevent and treat this disease.

Open pollution compounds such as nitrate, nitrite and ammonium acute or semi-acute water poisoning, especially juveniles’ fish create a short-term and long-term depending on the concentration impairs physiological activities and cause of death is unknown. Most affected by the contamination of farmed fish, their immune system is compromised. The main toxic reactions due to the conversion of nitrates in the water carry oxygen to the forms that are not capable of carrying oxygen. Nitrate toxicity on aquatic animals by increasing the concentration and exposure time increases. In contrast, nitrate toxicity may be associated with increasing body size, increase in water salinity, and reduced environmental sustainability. Fresh water animals seem to be more sensitive to nitrate is marine animals. Nitrate concentrations around 10 mg (maximum for drinking water according to Federal America) can have negative effects, at least in the long term exposure, freshwater invertebrates, fish and amphibians influence. Safe area under the concentration of nitrate to protect freshwater animals susceptible to nitrate contamination is recommended. In addition, the maximum level of 2 mg to protect the most sensitive freshwater species would be appropriate. In the case of marine animals, the maximum level of 20 mg is generally acceptable. However, in the early developmental stages of some marine invertebrates that have adapted well to the low nitrate concentration, may be more susceptible to nitrate are sensitive to freshwater invertebrates.