Zadorozhnii M. Peculiarities of growing African clary catfish (Сlarias gariepinus) in experimental conditions at natural temperatures

For the first time, research has been conducted on the feasibility of cultivating and increasing the survival rates of African catfish grown in concrete pools and earthen ponds under the conditions of the Polissya region of Ukraine, as well as comparing the efficiency of using floating and sinking feeds for catfish cultivation in these conditions. For the first time, research on low critical temperatures and the period during which catfish can withstand their impact without negative consequences has been conducted. The economic efficiency of African catfish cultivation during the growing season in earthen ponds and concrete pools has been evaluated. As a result of the conducted research, it was established that for further effective cultivation in pond conditions in the north of Ukraine, it is possible to rear stocking material at water temperatures corresponding to the specific climatic conditions of the area. It was established that rearing African catfish fry at temperatures ranging from 20 to 24° C reduces cannibalism rates by 6-10 %. It has been found that the pool method of cultivation using floating feed is more effective in terms of survival rates (75.95%) compared to the pond method. In the pond method, to achieve better survival results (66.25%), the use of sinking feed is recommended. The average individual mass of fish (in ponds) that received sinking feed was 166.05 grams, compared to fish that received floating feed – 158.05 grams. The highest growth rates were observed in the last decade of August when the average daily water temperature approached optimal values for African catfish (24–30° C). The research results indicate that when cultivating African catfish with an initial mass of 6.3±0.5 g in water bodies with water temperatures below the optimal (24° C), the fish size may not reach marketable weight during the growing season. The results of our research on the behavioral reaction to decreasing water temperatures (from 20 to 12° C) confirm that C. gariepinus can withstand a decrease in water temperature to 16° C without significant losses and can even adapt to such conditions in the long term. At a temperature drop to 14° C, the fish can survive for 36 hours, allowing fish farmers to respond to this problem in time. If the temperature drops to 12° C, this period is about 24 hours. Our studies confirm that fish can withstand a temperature of 10° C for two hours, after which they must be 8 moved to warmer water, raising the temperature by at least 4° C. The research results on the behavioral reaction to water temperature drop to 10° C during outdoor aquarium trials at an air temperature of -6° C indicate the negative impact of low air temperatures. Two-hour exposure to frost led to the death of the experimental groups.