International Journal of Aquaculture, 2025, Vol.15, No.3, 135-148 http://www.aquapublisher.com/index.php/ija 137 breeding systems with large water quality fluctuations, tilapia can adapt to survival better. This broad salt and water quality adaptability provides the possibility for tilapia to breed in unconventional environments such as coastal tidal flats and brackish bays, and also helps them to colonize and spread in foreign waters. Figure 1 Exposure of Nile tilapia to lethal cold stress caused extensive tissue damage. After being held at 12 °C for 72 h, both the normal fish (NO, individuals that could swim normally at the sampling time) and those lost equilibrium (LE) were sampled. Ctrl indicates fish not exposed to cold stress (Adopted from Liu et al., 2022) 2.3 Hypoxic tolerance and environmental stress response mechanism Under intensive breeding conditions, low dissolved oxygen is one of the common environmental stresses faced by fish. Compared with many sensitive fish, tilapia exhibits strong hypoxia resistance and corresponding physiological response mechanisms. When dissolved oxygen in the water drops, tilapia can absorb oxygen by increasing the swing frequency of the gill cover and floating to the water meter to breathe air to relieve hypoxia pressure (Obirikorang et al., 2023). In addition, the number of red blood cells and hemoglobin content in the blood can be upregulated under low oxygen conditions, improving the blood oxygen carrying capacity. Research has
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