First, the moving zebrafish was detected and tracked in the video using background subtraction and object tracking, which was developed using Matlab programming language with its built-in image processing toolbox. First, a median frame of the video is chosen as the background frame, where the intensity value of each pixel of this background frame is calculated as the median value of all intensities values of same pixel location of all frames. Next, the fish body is tracked as follows. The fish object is detected by subtracting each frame with the background frame. The largest connected component in this Diatrizoic acid difference image is selected as the fish body. Then, the boundary of the fish body is extracted, followed by various Cyproheptadine hydrochloride sesquihydrate quantitative measurements that are obtained as follows. Among various developed motion representations in the literature, the silhouettes-based features are desirable for motion representation since it is invariant to luminance, color and texture of the moving objects as well as the background. By tracking the fish, we were able to provide each zebrafish a unique label that enables individual tracking, and create temporal profile for analysis of individual motion activity. We further manually split the video sequence into smaller video clips containing one full body waving cycle. A body waving cycle is defined as a video segment containing one body waving zebrafish, where the fish starts from the straight posture and then bends its body and finally returns to straight posture. We then extracted quantitative measurements of body waving behavior of zebrafish in a single body waving cycle. Given the segmented and tracked fish in each video frame using the aforementioned method, we extracted the skeleton of the fish and establish a geometrical model with twenty control points to describe the posture of fish. These control points are uniformly distributed along the fish body from the head to the tail. We defined the following two quantitative measurements of body waving behavior of zebrafish movements. To determine if zebrafish expressing mutant human CLCN1 showed differences in body bending during swimming, we used high frame video recording to track the fish body and measure its bending degree using body curvature and tail offset as parameters.