Cold stress in fish: global mechanisms, adaptive strategies, and translational solutions for climate-resilient aquaculture

Water temperature is a fundamental abiotic factor that governs fish physiology, behavior, and survival. Although anthropogenic climate change is characterized by long-term warming and an overall decline in the frequency and intensity of cold extremes, regional climate variability and episodic cold events can still expose wild and farmed fishes to abrupt or physiologically stressful low-temperature conditions. This review synthesizes research on cold stress responses in fish from tropical, temperate, and polar environments from physiological and molecular perspectives. Using a structured literature search of major scientific databases for studies published between 1976 and 2026, we synthesized evidence across species and thermal environments. Building on earlier reviews, this cross-species synthesis links physiological, cellular, and molecular mechanisms of cold response with their implications for aquaculture management. Tropical fishes possess narrow thermal tolerance coupled with high vulnerability, whereas temperate species rely on metabolic and behavioral adjustments, and polar fish mostly depend on antifreeze proteins (AFPs) and cold-adapted enzymes. Exposure to low temperatures can elicit both detrimental stress effects and compensatory acclimatory responses, with their relative importance depending on the magnitude and duration of cooling, species-specific thermal limits, and prior thermal history. When cold exposure exceeds physiological tolerance, it may result in metabolic disruption, oxidative stress, osmoregulatory disturbance, immune suppression, and alterations in the gut microbiota. In contrast, modulation of MAPK and FoxO signaling, non-coding RNAs, and epigenetic regulation may participate in compensatory cellular responses that support physiological acclimation and, where demonstrated across generations, potentially contribute to longer-term thermal adaptation. Environmental management, dietary supplementation, selective breeding, pre-winter conditioning, and disease control represent potential strategies for mitigating cold-related losses in aquaculture, although the strength of supporting evidence and practical applicability vary among interventions, species, and production systems. We further identify critical knowledge gaps concerning long-term acclimation, transgenerational epigenetic inheritance, and interactions among multiple stressors. A key translational priority is to convert mechanistic indicators of cold tolerance into experimentally validated nutritional, breeding, and husbandry interventions that account for species-specific thermal biology and production conditions.