Mystus macropterus,which belongs to the Bagrdae family of the Siluriformes order of Osteichthyes,was a fast-growing and large economic fish species found naturally in the mainstream and tributaries of the Yangtze and Pearl Rivers.It had high levels of protein,fat,essential amino acids,and umami amino acids,making it highly valued for consumption.However,the lack of breakthroughs in large-scale breeding of this species had hindered its industrial development.Temperature was an important environmental factor that affect-ed the early growth and development of fish,playing a key physiological role in embryo hatching and metabo-lism regulation and serving as one of the decisive factors affecting embryo survival,fertilization rate,and hatching rate.M.macropterus fertilized eggs had weak adhesion,and hanging net hatching was currently the main method used in production.However,due to difficulties in water quality management,fertilized eggs were prone to generate water mold,resulting in unstable hatching outcomes.Therefore,exploring suitable tempera-ture and hatching methods for M.macropterus fertilized eggs was also an important research area in the artificial breeding process of this species.In order to achieve the above objectives,a single-factor experimental design was used to study the effects of different temperatures(22℃,24℃,26℃,28℃,and 30℃)and hatching methods(degumming hatch-ing[protease degumming,talcum powder degumming],hanging net hatching,and incubation box hatching)on hatching of M.macropterus embryos.The results showed that the hatching rate of M.macropterus larvae increased first and then decreased with the increase in hatching temperature,with the order of 22℃group(0)<30℃(12.51%)<24℃(17.95%)<26℃group(25.40%)<28℃group(30.51%).The differencesamongdifferenttemperature groupswere sig-nificant,and the binomial fitting obtained the optimal hatching temperature of 26.8℃.The survival rate after 24 hours of hatching showed that the 24℃group(54.76%)was significantly lower than the 26℃group(95.45%),28℃group(91.67%),and 30℃group(92.59%),and the differences between the latter three groups were not significant.The survival rates after 96 hours were 52.38%,90.91%,92.59%,and 40.74%,indicating that both low temperature(24℃)and high temperature(30℃)significantly affected the survival rate.The hatching time of larvae gradually shortened with the increase of temperature,and the range was 46～88 h.The results of the 24-hour good egg rate of the four hatching methods showed that the net hanging group(48.11%)was greater than the incubation box group(45.05%),protease degumming group(19.98%),and talcum powder degumming group(15.32%),and the differences among the four experimental groups were significant.The hatching rate was in the order of net hanging group(16.07%)>protease degumming group(12.08%)>incubation box group(9.61%)>talcum powder degumming group(9.26%).The hatching rate/good egg rate of the degumming group was the largest(all60.46%),which was significantly higher than the net hanging group(33.40%)and incubation box group(21.32%).Under the three protease degumming concen-tration gradients set in the experiment,the 24-hour and 48-hour good egg rates were significantly higher in the 0.75 g/L group than in the 3g/L and 1.5 g/L groups,and there was no significant difference between the latter two.The hatching rate showed a significant decreasing trend with the decrease of concentration,indicating that the egg membrane has a good protective effect on fertilized eggs while causing difficulties in the hatching process and leading to a decrease in the hatching rate.In Conclusion,temperature and hatching methods signifi-cantly affect the hatching.The optimal hatching temperature for M.macropterus is 26.8℃,and the preferred hatching method is protease degumming hatching,and the use concentration of protease was 3 g/L.The results of this experiment can help to achieve large-scale and efficient breeding of Grouper fish.
NETL
NSTL
维普
万方数据
