Along with the global industrialization, the problem of pollution has spread, especially the water pollution. Pollutants in many types (chemical, physical, radio-active or pathogenic microbial substances) enter natural water bodies such as lakes, rivers, oceans and so on, degrading the quality of water that has the harmful effects on several aquatic species living in it. As a result, many attempts have been made to develop the monitoring techniques to improve the ability of detecting more pollutants in shorter time, and at lower concentrations. Biological monitoring, or biomonitoring is a valuable assessment tool that receiving increased use in water quality monitoring programs, in which biochemical, genetic, morphological, and physiological changes in indicator species have been noted as being related to particular environmental stressors. Daphnia, a freshwater crustacean, has been extensively used as a model organism for toxicity testing and its toxicological reactions to environmental pollutants have been being well characterized. Together with this, achievements in genetic technology bring an advanced tool for studying water biomonitoring using this invertebrate. In the present review, the ability of using Daphnia in aquatic toxicological monitoring depending on “omic” approaches has been discussed shortly. © 2016, Korean Society of Environmental Risk Assessment and Health Science and Springer Science+Business Media Dordrecht.