A sterlet — seldom meeting in lower reaches of the river Ural Mountains a species of family sturgeon (Acipenseridae). Typically river fi sh, unlike migratory sturgeon, not making long-term migrations. Because of the small number a species it was not considered by statistics and practically it was not probed. The data on size — weight indicators of sturgeon in the Ural river, age structure, fatness and maturities of reproductive products in migration is cited. The sex ratio in the population is described. Appearance last years in Ural Mountains sterlet breeders, as well as to migrate down juveniles of this species.

The hydrochemical regime, fodder base (phytoplankton, zooplankton, zoobenthos) and feeding of juvenile fi sh in the water area of the Akhmat village in the Volgograd reservoir in August 2017 were studied. The water area was characterized by a high concentration of dissolved oxygen in the water and domination of chironomids in the zoobenthos. The most favorable conditions in the investigated water area were formed for feeding juvenile roach, which competed for fodder resources with bleak.

Presents the results of chemical studies of the state of the aquatic environment and bottom sediments of water bodies in three Park complexes in Moscow. Their tense ecological state is shown. There is an excess of standards for 10 chemical indicators, in water, and 3 in bottom sediments. Stated the need for hydraulic and biomeliorative events.

In this paper changes of length and age structure of a spawning part of population of blue whiting during considerable fl uctuations of its abundance and biomass are analysed. Dynamics of mass of individuals during given period was explored. In paper biological characteristics of fi sh as from scientifi c catches within the international survey of a spawning stock of blue whiting and from fi shery catches are considered. It is shown that the length-at-age composition of blue whiting is presented broader from fi shery catches, than from scientifi c catches, at the expense of the better catchability of fi shery trawls. It is shown that the weak recruitment of a stock observed in 2006–2010 has led to «aging of population», also to abrupt decline in biomass and abundance of a spawning stock in the conditions of intensive fi shery. It was concluded that a series of the numerous generations which were recruiting a spawning stock of blue whiting during 2011–2016 have rejuvenated population and also contributed growth of biomass despite intensive fi shery.

Integration of one of the most common directions in aquaculture, allowing to increase the output of products, rational use of available resources. However, integrated production can be unstable, which leads to negative eff ects in the production of several types of products. Integration is diff erent from combining productions. To integrate productions into systems, a balance between organisms is necessary. For the balancing of systems, determining the parameters of the biological components of the system, a preliminary calculation must be made, which determines the fl ow of matter and energy in integrated systems.

The authors studied annual reproductive cycles and gametogenesis of sterlet reared in recirculation aquaculture systems (RAS). It was established that sterlet sturgeons reproduce for the fi rst time at an age of 6–7 years in natural conditions (Terek river) and at an age of 2–3 years in RAS. The completion of vitellogenesis in natural conditions occurs slowly within a year and may be divided on two substages; in RAS this process completed quickly during 3–4 months and without distinct substages. Gonadosomatic indices are higher at all stages of gonad maturity in fi shes captured in nature in comparison with fi shes reared in RAS. In nature the gonadosomatic index ranges from 1,5 up to 2,5% in previtellogenic fi shes and from 16 up to 20% in premature ones, whereas in RAS these indices are lower: 0,38–1,75% in previtellogenic fi shes and 11,8–16,6% in premature and mature ones.

Researches of concentration and activity of lysozyme at fi ngerlings, yearlings and two-year of the pike perch of the fi rst generation who is grown up in installations of the closed cycle of water supply recirculation aquaculture systems are conducted. Researches were conducted in the fall or in the spring, applying standard techniques. It has been as a result established that at the fi rst stage of a domestikation the season of year exerts impact on concentration and activity of lysozyme.

The paper presents studies on the eff ect of the introduction in ration of probiotics and biologically active additives on the growth and physiological state of fi sh. Positive results were obtained. Thus, the addition in a ration of a probiotic «Subtilis» in the amount of 0,5; 1,5; 3,0 g/kg of feed resulted in an increase in the rate of growth of clarias catfi sh by 6,7–15,5%. This is especially evident during the fi rst stages of growing fi sh. Higher growth rates of catfi sh on the ration with the addition of «Subtilis» are accompanied by better indicators of blood biochemistry and feed payment. Cultivation of Nile tilapia on rations supplemented with 1, 3 and 5% «Metabolit Plus» also contributed to the obtainment of high fi sh-breeding indicators. The best results on the rate of fi sh growth, the effi ciency of feed use were obtained in the variant where 3% «Metabolit Plus» was added to the feed. In fi sh consuming «Metabolit Plus», less deposited in the body of internal fat, which indicates a high plastic metabolism. Along with this, these fi sh have a slow development of reproductive products, which makes it possible to maintain a longer period of growth of muscle tissue. Studies on the use of biologically active supplement «Sangrovit Extra», developed by Phytobiotics Futterzusatzstoff e GmbH (Germany), in feeding of a rainbow trout gave preliminary encouraging results. Trout that was consuming this additive, was more active, consumed food faster, grew more intensively