CBRCell Biology ResearchTBA2529-7627WHIOCE PUBLISHING PTE. LTD.10.18063/CBR.v7i2.1893ArticleResearch on the Physiological Mechanisms of Osmotic Pressure Regulation in Freshwater Fishhttps://artdesignp.com/journal/CBR/7/2/10.18063/CBR.v7i2.1893GaoJuan,GengWeihang2026722026-06-26Freshwater environments possess an overall osmotic pressure that is considerably lower than the body fluids of fish, which leads to chronic osmotic stress in freshwater fish with passive water absorption and ion loss. In order to maintain the dynamic equilibrium of water and ions for stable cellular metabolism, neural transmission, and organ function, freshwater fish have developed a comprehensive physiological system for osmotic regulation. By means of the coordinated operations of multiple organs that involve enzymatic reactions and hormonal regulation, they accomplish water excretion and ion reabsorption, thereby stabilizing the osmotic pressure of body fluids. This article, in a systematic way, elucidates the osmotic environmental stresses that freshwater fish are faced with, and it analyzes the osmotic regulatory functions of those key organs, such as gills, kidneys, intestines, and skin. It also elucidates the regulatory mechanisms of those critical enzymes and endocrine hormones. It summarizes the energy metabolism patterns and environmental adaptation characteristics within the realm of osmotic regulation, and it provides a whole-scale overview of the entire physiological mechanism of osmotic regulation in freshwater species. The study aims to clarify the fundamental physiological principles that underlie the osmotic balance in freshwater fish, and it offers theoretical foundations for aquaculture water quality management, stress-resistant fish breeding, and aquatic organism physiological research.Freshwater fish,Osmotic pressure regulation,Physiological mechanism,Ion transport,Environmental adaptation

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