Increasing water temperatures and salinity intrusion due to climate change are serious challenges for freshwater aquaculture. In this study, we assessed the combined effects of salinization at 0, 6, and 9‰ and water temperatures of 28, 31, and 34 °C on the survival and growth rates, and feed utilization, of freshwater snakehead Channa striata. We also assessed feed digestibility in snakeheads to explore their physiological mechanisms. The lowest survival rate (66.7%) was found at 34 °C-9‰. The highest daily weight gain of 0.72 g/day was found at 34 °C-0‰, while the second highest (0.62 g/day) was at 31 °C-0‰. Chymotrypsin activity increased at higher temperatures; the activities of α-amylase and pepsin were lowest at 34 °C-9‰. The highest apparent digestibility coefficients (ADCs) for dry matter (80.3%), protein (95.3%), and lipid (97.9%) were observed at 31 °C-0‰ (p < 0.05). Elevated temperature (34 °C) combined with high salinity (9‰) was lethal for one-third of the fish. The lowest ADC and α-amylase activities led to the highest feed-conversion ratio. Snakehead growth rates were highest in the 31 °C-0‰ and 34 °C-0‰ treatments. The combined highest salinity and highest temperature treatment (34 °C-9‰) decreased snakehead growth, feed utilization efficiency, feed digestibility, and enzyme activities (except for chymotrypsin).

中文翻译：

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盐渍化加剧了温度升高对越南湄公河三角洲常见的热带淡水水产养殖鱼类 Channa striata 的影响

由于气候变化导致水温升高和盐分入侵是淡水水产养殖面临的严峻挑战。在这项研究中，我们评估了 0、6 和 9 ‰ 的盐渍化以及 28、31 和 34 °C 的水温对淡水鳜鱼的存活率和生长率以及饲料利用率的综合影响。我们还评估了蛇头的饲料消化率，以探索它们的生理机制。在 34 °C-9‰ 时发现最低存活率 (66.7%)。在 34 °C-0‰ 时发现每日体重增加最高 0.72 克/天，而次高（0.62 克/天）在 31 °C-0‰ 时。胰凝乳蛋白酶活性在较高温度下增加；α-淀粉酶和胃蛋白酶的活性在 34 °C-9‰ 时最低。干物质 (80.3%)、蛋白质 (95.3%) 和脂质 (97. 9%) 在 31 °C-0‰ (p < 0.05) 下观察到。升高的温度 (34 °C) 加上高盐度 (9‰) 对三分之一的鱼来说是致命的。最低的 ADC 和 α-淀粉酶活性导致最高的饲料转化率。在 31 °C-0‰ 和 34 °C-0‰ 处理中，蛇头的生长率最高。结合最高盐度和最高温度处理 (34 °C-9‰) 降低了蛇头的生长、饲料利用效率、饲料消化率和酶活性（糜蛋白酶除外）。