International Journal of Aquaculture, 2025, Vol.15, No.3, 135-148 http://www.aquapublisher.com/index.php/ija 136 water quality deterioration and disease outbreaks, which poses a test on environmental carrying capacity (Acosta-Pérez et al., 2022). Secondly, genetic factors play a key role in the improvement of tilapia species and the improvement of breeding performance. By introducing genetic selection and breeding technology, people have cultivated new varieties such as GIFT tilapia that grows faster, as well as anti-strepococcus strains with stronger disease resistance, providing an excellent seedling foundation for industry expansion. However, variety introduction and hybridization also bring ecological risks such as alien species invasion and genetic pollution, and it is necessary to take into account biosecurity and diversity protection while developing production. The research on global expansion of tilapia is of great significance. On the one hand, analyzing the impact of environmental adaptability and climate change on the tilapia farming map will help predict the change trends of future farming areas and guide countries to reasonably plan their breeding layout. On the other hand, summarizing the role of genetic improvement in the development of the tilapia industry can provide ideas for further improving breeding efficiency and stress resistance. This study systematically explains how environmental and genetic factors shape the global pattern of tilapia aquaculture based on environmental adaptability, climate change impacts, genetic improvement, germplasm resources, typical national cases, ecological risks and future technical outlooks, hoping to provide reference for industry managers and scientific researchers. 2 Environmental Adaptability: Ecological Plasticity of Tilapia 2.1 The performance of wide temperature and wide salt characteristics in different ecological regions Tilapia is known for its wide temperature properties and can adapt to a variety of water temperature environments from subtropical to tropical. In Africa, Nile tilapia (Oreochromis niloticus) can survive in the water temperature range of 1 438 °C, with an optimal growth temperature of about 2 532 °C; extreme temperatures below 15 °C or above 40 °C can cause stress and death (Zhou et al., 2022). In the introduced regions, tilapia exhibits excellent temperature adaptability. Farming practices in southern China show that high temperatures in summer (the lake water temperature often reaches above 30 ℃) do not affect the feeding and growth of tilapia; and when the water temperature drops to around 15 ℃ in winter, tilapia can still survive and survive the winter even though the feeding intake drops. This is because tilapia can cope with temperature changes by regulating metabolic rates and activity behavior, reducing oxygen consumption and eating to preserve energy when water temperatures decrease (Figure 1) (Liu et al., 2022). In addition, there are differences in the cold tolerance of different species of tilapia. Blue tilapia (Oreochromis aureus) is relatively cold-resistant and can tolerate low temperatures around 10 °C, so it is often used to hybridize with Nile tilapia to improve cold resistance. There are studies that have obtained strong cold-resistant tilapia strains through hybrid selection and survival rates significantly higher than those of ordinary strains in acute cooling tests. 2.2 Water quality adaptability and aquaculture density regulation Tilapia not only can adapt to different water temperatures, but also has a wide tolerance range to salinity, showing wide salt properties. Although tilapia is native to freshwater basins, it can survive in salty freshwater and offshore high salinity environments. Experiments have shown that Nile tilapia can grow normally in salt water with a salinity of 15‰~20‰, and some individuals can even tolerate short-term exposure of seawater salinity (about 30‰) (Mirera and Okemwa, 2023). Field surveys on the Brazilian coast recorded tilapia invasion of estuary and coastal wetland ecosystems, showing that the species has the potential to utilize brackish and seawater environments. The general salt adaptability of tilapia is partly attributed to its well-developed osmotic pressure regulation mechanism in the body: when in a high-salt environment, tilapia excretes excess salt in the body by increasing the number of chlorine cells in the gills and drinking water, maintaining fluid balance (Huang et al., 2025). In addition, tilapia has a strong tolerance to water quality and shows certain tolerance to higher concentrations of ammonia nitrogen and nitrite. A study based on carbonate alkalinity stress showed that the semi-lethal alkalinity (pH in carbonate) of Nile tilapia at 96 hours acute exposure ranged from 6.25 g/L to 9.01 g/L, which is weaker than extremely alkali-resistant fish but is more tolerant than most freshwater fish. Under the conditions of gradual domestication, increasing the alkalinity of water can significantly improve the alkali resistance of tilapia juvenile fish. Therefore, whether in brackish ponds, saline-alkali waters, or in intensive
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