Abstract: Semicarbazide (SEM) is widely monitored as a metabolite of the nitrofuran antibiotic nitrofurazone (NFZ). In recent years, frequent occurrences of excessive SEM residues in aquatic products have seriously hindered the export trade and sustainable development of the Chinese aquaculture industry. Studies have shown that SEM derives from both exogenous and endogenous sources. Exogenous sources include illegal drug use, contamination from water, feed, and algae, and chemical reactions during processing. Endogenous formation, conversely, occurs through pathways such as amino acid metabolism, the urea cycle, and chitin metabolism. This review systematically examines the sources, formation mechanisms, and metabolic behavior of SEM in aquatic products with a focus on advanced detection methods, including metabolomics, transcriptomics, and high performance liquid chromatography (HPLC). Furthermore, targeted control strategies are proposed, encompassing aquaculture environmental management, optimization of processing procedures, and regulation of key metabolites. This review aims to provide a scientific foundation for the effective prevention and control of SEM contamination in aquatic products in China.