In order to develop an early-warning biosensor system based on Japanese medaka (oryzias latipes) for predicting the impact on health of long-term and low-level exposure to indoor chemical compounds, we investigated the effect on behavioral changes of medaka exposed to Dichlorvos (2,2-dichlorovinyl dimethyl phosphate, DDVP), which is a kind of agricultural compounds having a potential to flows into indoors and be inhaled by resident and may affect residents' health badly and fatally in agricultural districts, as well as Formaldehyde and Toluene which are representative indoor chemicals. We used a laboratory water-quality measuring instrument to observe behavioral changes of fish. During the experiments, the three-dimensional coordinates of the fish are recorded by two CCD cameras every three seconds. P value of <0.05 was considered to indicate significance. When exposed to these chemicals in water, the fish showed the altered behaviors compared to one under a control treatment, e.g. body movement distance and duration time near the lower water column by the fish significantly decreased, while body angle near the upper water column and duration time near the upper water column by the fish increased compared to the normal state.
