Drug residues in food animal tissues and products pose a potential threat to public health and environmental safety. The effects of drug residues in animal foods on human health are mainly manifested in allergies and allergic reactions, bacterial drug resistance, mutagenic effects, carcinogenic and hormone effects. Hence, the monograph here intends to introduce several aspects for the application in aquatic products. The establishment of simple, reliable, rapid and sensitive residue detection methods is very important for ensuring the safety of animal-derived foods, and promoting the stable and healthy development of the aquaculture industry. This book, further refined at Bishan Ecology & Environment Bureau in Chongqing, has expanded our understanding towards the determination of drug residues by LC-MS and relevant applications.