Phosphatidylcholine (PC) is a major component of membrane phospholipids and plays essential biological roles. The primary pathway for PC synthesis is the CDP-choline pathway, in which CTP: phosphocholine cytidylyltransferase (CCT) functions as the rate-limiting enzyme and is a key factor in maintaining PC homeostasis. CCTα, one of the major isoforms of the CCT family, is widely distributed across mammalian organs and tissues, and plays crucial roles in membrane biogenesis and lipid metabolism. Recent studies have shown that CCTα is also present in fish and exerts important regulatory functions in fish lipid metabolism. This review summarizes the functions and regulatory mechanisms of CCTα in both mammals and fish, with a focus on its roles in membrane biogenesis and lipid metabolism. Additionally, the potential of CCTα as a molecular target for regulating nutritional metabolic disorders in fish is explored, aiming to provide a theoretical implications for the healthy development of aquaculture.