Ship sturgeon (Acipenser nudiventris Lovetsky, 1828) is one of the most endangered species. To restore the wild ship sturgeon population, the assessment of the quality of the offspring from farmed broodstock is necessary.
The objective of this study is to evaluate the anesthetic effects of clove oil on the different-sized ship sturgeon juveniles by measuring the times to anesthesia and recovery. The experiment was conducted in 2018 and 2020 for juveniles aged 50, 70, 90, 120, and 150 days at a water temperature of 20-22 °C, oxygen - 6.8-7.5 mg/l with the addition of an aqueous emulsion of clove oil of 0.07 ml/l. Each anesthetic effect of clove oil was tested in three groups of fish with different body sizes.
The first stage (10-30 s), anesthetized juveniles showed excitement, with subsequent complete loss of equilibrium and tail fin movement stop, which was considered complete anesthesia.  
It is known that resistance to neurotropic drugs correlates with the overall viability of fish, which is determined by the best physiological state of low-sensitivity individuals.
In 2018, juvenile ship sturgeons were used, which were interpopulation hybrids of F3-F4 and entered anesthesia more quickly, but reanimated more slowly. In 2020, the experiments were conducted on juveniles of the Caspian populations generation F2, which proved to be more resilient and recovered faster. It was also found that the average juveniles in both experiments, at the age of 70 days and weighing 5 g, were the most resilient. 
This method can be used to immobilize juveniles and young sturgeon fish for various manipulations and studies where waste is not allowed. It can also be used as an assessment of physiological status for the development of therapeutic and preventive measures and the release of high-quality juveniles.

ship sturgeon,health and welfare,anestezia,clove oil,eugenol,Acipenser nudiventris