Abstract:

To provide a feasible technical scheme for the overwintering Leiocassis longirostris culture in the Yangtze River Delta, the feeding and growth of the Leiocassis longirostris under the overwintering culture mode were studied. The overwintering rearing technology and the growth characteristics of 0⁺ age young fish and 1⁺ age fish Leiocassis longirostris under greenhouse pond condition in 2021—2022 and 2022—2023 were explored and investigated in this study. The initial body length and mass of 0⁺ age young fish Leiocassis longirostris were 14.78 cm and 40.83 g, with the stocking density of 83340 tails/hm² (3402.60 kg/hm²). The initial body length and mass of 1⁺ age fish Leiocassis longirostris were 21.99 cm and 156.86 g, with the stocking density of 42525 tails/hm² (6670.20 kg/hm²). The results showed that the water temperature could be kept above 11℃ and 10℃ under the greenhouse pond condition. During the pre-winter breeding period (December to the end of February), the feeding of Leiocassis longirostris was relatively stable. Since March, with the increase of water temperature, the daily feeding amount rapidly increased. The cumulative feeding amount during the overwintering period was 4009.00 kg/hm² and 4715.00 kg/hm², respectively. After 150-152 d of rearing, the growth rate of 0⁺ age young fish and 1⁺ age fish Leiocassis longirostris were 23.7% and 10.2%, weight gain rates were 131.8% and 51.7%, specific growth rates for body length were 0.140%/d and 0.065%/d, specific growth rates for body mass were 0.553%/d and 0.278%/d, daily growth rates were 0.023 cm/d and 0.015 cm/d, and daily mass gain rates were 0.354 g/d and 0.541 g/d, respectively. The condition factors of 0⁺ age young fish and 1⁺ age fish Leiocassis longirostris at harvest time were 1.52 and 1.62, the survival rates were 92.8% and 99.7%, the yield per unit area was 7317.00 kg/hm² and 10093.65 kg/hm², and feed coefficients were 1.02 and 1.38, respectively. In conclusion, the water temperature can be kept above 10℃ under greenhouse pond condition, Leiocassis longirostris may maintain continuous feeding and exhibit good growth performance. This study provides technical support and theoretical basis for the facility culture of Leiocassis longirostris in the Yangtze River Delta region.

Key words: Leiocassis longirostris, 0⁺ age young fish, 1⁺ age fish, greenhouse pond, overwintering culture, growth performance, water temperature control, body length growth rate, weight growth rate, specific growth rate, daily growth rate