A robot accepted by animals as conspecifics is a very powerful tool in behavioral biology, particularly in studies of gregarious animals. In this paper we present a robotic zebrafish designed for experiments on the collective animal behavior. The robot consists of two modules: a replica fish fixed on the magnetic base and a miniature mobile robot guiding the replica fish from below the experimental tank. The size of the mobile robot is 45x15x73 mm that makes it possible to use it in a group of robots forming a dense artificial fish school. The experiments showed that the robot can reach speed and acceleration maximums reported for zebrafish, thus its parameters satisfy the conditions necessary for the next step that will be interaction tests with the zebrafish.