Peculiarities of growth of age-1+ paddlefish (Polyodon spathula Walbaum, 1792) in conditions of a pond fish farm in the forest-steppe of Ukraine

Purpose. To investigate the peculiarities of growth of age-1+ paddlefish depending on water temperature and quantitative parameters of zooplankton development in ponds of the forest-steppe zone of Ukraine. Methodology. Age-1+ paddlefish, a North American zooplanktophagus were reared in polyculture with cyprinids in a 72-hectare pond using semi-intensive technology. The stocking density of age-1 paddlefish with an average weight of 86.5 g was 59 fish/ha, with a total stocking density of 2,402 fish/ha for all objects of polyculture. The intensification measures included fertilization of ponds with traditional organic fertilizers and feeding of carp with feed mixtures based on waste from the processing of agricultural raw materials of plant origin. The study of the intensity of development of the natural food supply and physicochemical parameters of water was carried out according to the methods generally accepted in hydrobiology and hydrochemistry. Determination of piscicultural parameters and growth characteristics of age-1+ paddlefish was carried out using methods common in ichthyology based on the dynamics of body weight gains in absolute and relative values. Findings. The conditions of the pond environment during most of the period of rearing of age-1+ paddlefish met the biological requirements of this species. A periodic decrease in the content of oxygen dissolved in water to 3.3-3.5 mgO2/dm3 was noted, which could negatively affect the growth of fish. Water temperature during the fish breeding period varied between 9.8-26.5oC. The average seasonal biomass of phytoplankton and zooplankton of the pond was 16.49 mg/dm3 and 3.92 g/m3, respectively, with a predominance of Cladocera and Copepoda (respectively, 61.0 and 34.5% in the average seasonal biomass) in the quantitative composition of zooplankton. As a result, age-1+ paddlefish reached an average weight of 1318.3 g with a fish productivity of 45.6 kg/ha and a total pond fish productivity of 1162.6 kg/ha. Maximum relative weight gains of paddlefish of 4.25–4.37% per day were observed during the first half of the growing season (mainly in June) at a water temperature of 22–25oC during the period of increase in zooplankton biomass from 3.79 to 10.11 g/m3. Originality. New data were obtained on the growth characteristics of paddlefish depending on environmental conditions of the ponds of the Forest-Steppe zone of Ukraine. Practical value. The study results can be used in the process of improving pond aquaculture technologies in Ukraine.