Body length up to 5 cm. Life expectancy up to 5, mainly up to 3 years. The body is elongated, laterally compressed, rather high, covered with large, easily detachable scales when touched. The head is noticeably flattened from above. The lateral line is absent. In the side row there are 31 flakes. The anal fin is long, in males it is not modified, like in gambusia , for gonopodia . The mouth is small, upper, slit-like, the jaws are armed with small simple pointed teeth. The eyes are big. The peritoneum is black. The color is variable, the back and sides are from silver-yellow to light brown in color, the belly is gray. On the back, from the back of the head to the beginning of the dorsal fin, there is a dark strip, on the sides along the middle of the body there is an indistinct dark strip. Abdominal and anal fins with black dots.
Characteristic sexual dimorphism . The male has a more intense color, a little more pigmented; its rays of the dorsal and anal fins are noticeably longer than that of the female.
The natural range of the species includes water bodies of the peninsula of Korea and China , and possibly Japan (the range requires clarification) - from the Mekong to the Red and rivers of southern China [1] . This species is found in most parts of the Korean Peninsula [2] . It should be noted that the Japanese species Oryzias latipes is widespread in the rivers of the coast of South Korea [3] .
During the introduction of Amur fish, it was imported from China to Kazakhstan , where in 1971 it was first recorded in the Ili River basin, where it has now become a mass species [4] [5] .
It was introduced in 1974 to the Krasnodar Territory from Kazakhstan [5] . It was released in 6 reservoirs, 5 of which were located within the city of Krasnodar and 1 in the vicinity of Anapa . It successfully bred in two reservoirs of Krasnodar, it was noted in the Anapka River, and in 1989 it was found in rice fields of the Maryano-Cherbugol irrigation system [6] . In July 2001, it was found in the reservoirs of the Kuban River system near the villages of Kurgan and Protichka [5] .
In Ukraine, it was first recorded on June 15, 2003 in the Obitochnaya river ( Zaporizhzhya region , within the city of Primorsk, 2 individuals) [7] [1] .
The species was also introduced in the United States - in Florida .
In addition to the use of species distribution factors outside the natural range to control the malaria mosquito, there can be other reasons, among which are the most likely unintentional importation of fish stock into fish farms, as well as the use of an aquarium with an accidental release into natural water bodies [8] [9 ] ] .
Freshwater schooling fish in shallow sections of rivers, their floodplains and other bodies of water. It keeps in flocks in shallow water and almost always adheres to one place. It reaches puberty in the first year of life, in particular already in June-August, with a body length of more than 1.2 cm. Propagated (water bodies of Kazakhstan) in April-September. A female can lay up to 2000 eggs per season. Portion spawning, usually occurs among vegetation in the dark. At a water temperature of 26 ° C and higher, the female lays eggs every day, up to 50 eggs at a time. The spawning process itself is interesting: first, the female releases caviar, which hangs like a bunch of grapes under the anus, where it is fertilized by the sperm of males, and only after a while later disperses it into the underwater vegetation. At a water temperature of 24-28 ° C, larvae hatch from eggs 10-15 days after fertilization. It feeds on plankton, small crustaceans, worms, etc. algae of different systematic groups, but insect larvae, including mosquitoes, predominate in the food of adult individuals.
