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Identification of different fish species and gender identification to those who propagate the fish scientific ally is necessary. Silver dollar is characiform genus Metynnis that often has ornamental aspects. Its scientific classification is unsatisfactory today. Ahl (1924) identified 24 species of the fish and Goslyine (1951) the number of valid species reduced to 6. Zarske and Grey (1999) have named the 11 valid species of the genus. Among the species of this genus are M. maculatus and M. otuquensis finest scales. The number of scute (40) in M. lippinocottianus is the highest. M. luna, M. orinocensis and M. guaporensis has the highest number of gill raker. M. luna body height is more than other species. Anal fin and colorful patterns on the body is usually used to identify the sex of these fish.

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In this research, the effects of different levels of prebiotic Immunogen on reproductive performance of angelfish (Pterophyllum scalare) were investigated. 16 pairs of angelfish breeders with average weight 8.67±033 were fed till saturating for 50 days and after this period, reproductive indices such as absolute fecundity, hatching percent, larval survival until yolk-sac absorption, gonadosomatic index and larval tolerance against high temperature stress to amount 10 °C were evaluated. The experiment was carried out in completely randomize design with four levels 0 (control), 1% (T1), 1.5% (T2) and 2% (T3) that each treatment had 3 replications.  Amount of absolute fecundity in T2 significantly was higher than control (p<0.05), but there were no significant differences among T1, T2, T3 and between control with T1, T3 (p>0.05). Gonadosomatic index in T2 and T3 was upper than control and T1 that this difference was significant (p<0.05). The highest hatching percent was observed in T2 (75±9.28) and T3 (66.95±8.85), respectively, so that significant differences (p<0.05) was seen among T2 with control and T1. In addition, there were no remarkable differences in larval survival until yolk-sac absorption and larval tolerance against thermal stress (p>0.05). Regarding to findings of this research, addition prebiotic Immunogen at level of 1.5% to angelfish breeders' diet was recommended for reproductive indices promotion. 

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he use of nano-technology and nano-enabled products in the industry is the widely expanding. The nanoparticles used in aquaculture in order to cure disease and to control the bacterial load of water can be verified. Nanotechnology is the use of nano-scale structures (at least one Bd100-1 nm), respectively. So that the scale has a wide application in science, chemistry, biology and medicine. Today, with the increasing development of nanotechnology much concern about the potential risks of nanoparticles containing materials release to the environment has been created. So that the release of these substances into the aquatic ecosystems can have undesirable effects on their life species. To evaluate the toxicity of environmental pollutants in fish are different physiological parameters such as including histology. According to the research of nanoparticles affect the tissues of the skin, gills and liver, kidney and intestines is. In this study, the effects of nanoparticles on various of fishs tissues are examined.

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Primary tissue culture, its applications and using this method for propagating of oocyte follicular
cells were
explained. Material and methods for isolating and culturing of follicular cells from Sterlet sturgeon,
Acipenser ruthenus in L-15 culture medium that complemented with FBS and antibiotics,
evaluation of their propagation and steroids hormones secretion expressed. According to obtained
results, cultivated follicular cells could be propagated and secret Testosterone (T), Estradiol-17&beta
(E2) and Progesterone (P4) hormones in culture medium. In attention to obtained consequences
from culturing of follicular cells in Sterlet sturgeon, Common carp, Cyprinus carpio, European sea
bass, Dicentrarchus labra and primary culture of oocytes in some fish such as Gold fish, Carassius
auratus Medaka, Oryzias latipes Guppy, Poecilia reticulate Fathead Minnow, Pimephales
promelas, Persian sturgeon, Acipenser persicus, and a hybrid sturgeon, Bester, developing similar
in vitro systems for ovarian follicular cells and oocytes in other fishes that will be useful to
functional studies and serves a valuable tool in study on oocytes and follicular cells.

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The fish color is one of the most important qualitative properties in aquaculture. Pigments of diets
are responsible for creating a wide range of color in aquatic animals. Although, the pigments are
known as the color changer in fish, other functions are attributed to pigments, such as antioxidants,
growth promoter, survival and reproductive effects in fish. In this article sources, amount, stability,
structure, variety, performance, digestibility and changing of carotenoids in aquatic animals were
studied. Moreover, some new structures of carotenoids in Salmonids, Cyprinidae, and Ornamental
fish, Crustaceans, Sponges and Clams were introduced. Finally, the role of carotenoids in fish and
their effects on reproduction, fertilization and larval growth rate were discussed.

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Stability, physical form diet pellets are very important during  consumption and prevention of early leaching into water. In sustainable aquaculture quality of diet is very important, Because about 60% of the total cost is related to production fish diet, diet quality plays a vital role in aquaculture. Therefore, during the preparation of a high quality diet it is necessary to pay attention to cost, stability, physical form and feed requirements. Feed stability could be increased by using binders. So, binders can improve the pellet strength and reduce the corrosion rate during the processing and transport of feed. On the other hand, pellet leaching in water cause the loss of ingredients and reducing the nutritional value of feed. Moreover, deposition the material in the bottom of the pool and their metabolism will increase the BOD in water. So, pathogens and consequently their secondary effects have good condition to grow. The best binders are those that in addition to increase the feed strength can decrease the expenditure and be available. Different types of binders are included: carboxymethyl cellulose, corn starch, sodium bentonite, aqua cube and so on. The aim of the present project was to study the variety of used binders in aquaculture and introduction of the best of them with the optimum efficiency. 

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The aim of hybridization is to get the generation which has better characters than parent. Because of pretty apparent and different species, ornamental fish attract peoples^, attention over the world and there was limited study about them so the purpose of this study was to investigate the hybridization between guppy and molly, growth performance and reproduction indices next generation. Virgin females and males aged 2 weeks were used in the experiment. 4 females and 2 males were stored per a glass aquarium (40ₓ30ₓ30). Fish were randomly stored in 4 treatments and 3 repeats including male guppy and female molly, male molly and female guppy, male guppy and female guppy and male molly and female molly and fed biomar. At the end of trial the possibility of molly and guppy hybridization was evaluated. The results indicated that no pregnancy and larva were seen in prospective treatments.

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The growth hormone in fish is involved in most of the physiological processes in the body, including the growth of soft and hard tissues, protein metabolism, lipid and carbohydrate, ionic regulation and osmotic balance, reproductive function, and immune system. Since the study on the use of growth hormone in ornamental fish is not available, the present study aims to regulate neuroendocrine growth of the growth hormone in red fish as one of the most common ornamental fish, and the performance of the growth hormone in the immune system, osmotic regulation, and expressions as the most important The effects of this hormone proven in other aquatic animals have been shown to be used in applied research for the use of growth hormone in ornamental fish and other aquatic animals.

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A new and suitable breeding method for inducing asexual or sexual reproduction (opium pneumonia) of Daphnia Magna is described in the laboratory. Drying and dehydration cause the production of epiphium epiphium with rapid hatching. In the present study, the effect of many different parameters such as pesticides, light periods and light intensity, sediments, culture oxygen levels, dark period, and ultraviolet rays, and The effect of temperature on Daphnia production was reviewed. In the present study, it was shown that the prerequisite for finding the optimal conditions and the highest hatch rate and obtaining the optimal breeding technique need to the present studies more. But in general, in the optimal laboratory method, dormant eggs of cladoceran need a dark period of about 2 weeks (different in different species) and then drying, and then to revive that, light and oxygen conditions and free of herbicides are required.

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The ornamental fish industry is of particular importance as a growing industry and accounts for a significant number of exports and imports from many countries. Fighter fish is one of the most popular fishes of breeders and home aquarium owners due to its high rent diversity, caudal fin scales, body shape, and tolerance to environmental conditions. The individual is sold. The feeding of fish larvae is one of the most important parts of the aquaculture industry, which can increase the survival of the larvae. To investigate the effect of infusoria, yeast, and artemia nauplii, an experiment was conducted for four weeks for fighter fish larvae. After hatching, they were collected and fed with live food in separate aquariums. The results showed that the fighter larvae fed with Artemia nauplii had the highest survival rate (48±2%) baker's yeast with 23±1%, and finally the fed larvae. With infusoria, 17±1% had survival. The results showed that Artemia nauplii was the best food among these used foods.
 

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The aquaculture industry is increasingly facing the challenge of fungal toxins and harmful compounds in fish feed. These toxins, which are mainly called mycotoxins, can cause a wide range of negative effects on the health and performance of aquatic animals. Some of these problems include reduced growth, weakening of the immune system, damage to the liver and kidneys of aquatic animals, and finally their death. Contamination with mycotoxins in aquatic food not only endangers their health, but consumption of contaminated aquatics may be a way for mycotoxins to enter the human food chain and threaten food security and public health. The most important mycotoxins in agricultural products and fish feed are aflatoxins, fumonisins, ochratoxins, trichothecenes, and zearalenone. To use crops in aquaculture production, efforts should be made to control their contamination with fungi and mycotoxins. Toxin binders have emerged as an innovative solution to deal with these threats and play a vital role in improving aquatic health, and growth, reducing losses, meat quality, reducing breeding costs, and sustainability in aquaculture.

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In recent decades, due to the importance of using leeches in medical sciences and the treatment of many diseases, these creatures have been receiving a lot of attention. Leeches are hermaphrodites, But they do not have the ability to self-fertilize. Morphological studies on different leech species show that the position of male and female genital pores is of great importance. These pores are located in the leech's clitellum region. The clitellum region is responsible for reproductive behavior in leeches. This area is usually in the form of several swollen rings in the anterior part of the leech's body, which can be seen during reproduction. Mating in leeches is through internal fertilization and the exchange of sperm into the reproductive organs of another female leech. The glands in the clitellum region produce nutrients and proteins necessary for the formation of the cocoon. The leech eggs are transferred into the cocoon from the pore of the female leech, and after about twenty days, the leech larvae come out of the cocoon. Currently, some leech species are in danger of extinction due to excessive use of leeches and indiscriminate harvesting, as well as due to environmental pollution in natural habitats. Reproduction and cultivation of leech help to maintain survival and prevent a decrease in the leech population. In order to have successful reproduction and breeding, it is important to know how the leech reproductive system works. This study discusses the function of the leech reproductive system, male and female organs, clitellum region, fertilization, cocooning, and larval production in leeches.