Abstract: The content of heavy metals in a certain tissue or organ of an organism may reflect the level of heavy metal pollution in the environment, but not any information of molecular level. Changes in biomarkers may be used for assessing level of heavy metal exposure and potential adverse effects on living organisms. Biomarkers can be sorted into three major categories: exposure biomarkers, effect biomarkers and susceptibility biomarkers. Principles for using antioxidant, genetic toxicity, acetyl cholinesterase, metallothionein and heat shock proteins biomarkers to monitor Cd pollution of water bodies, and status of their applications are addressed, in an attempt to provide some reference for future studies on mechanism of cadmium toxication of aquatic animals as well as a theoretical basis for prevention and control of heavy metal pollution and protection of the aquatic ecosystem.