Using EthoVision to quantify spontaneous swimming behavior in small groups of fish

Marc Ylieff and Pascal Poncin (Liège, Belgium). The aquatic environment does not facilitate the operation of image processing because of phenomena of reflection and refraction of light. In addition, the immobile camera placed either above (top view) or beside the aquarium (frontal or lateral view) gives a 2-D input image to measure animals swimming in a 3-D environment. However, with technical adaptations,  several individually identified fishes swimming freely in the adapted aquarium could be observed. The test results illustrate the possibilities and advantages of EthoVision in understanding the relations between fish and their biotic or abiotic environment.