A robot accepted by animals as conspecific is a very powerful tool in behavioral biology, particularly in studies of gregarious animals. In this paper we present the first results of acceptance of a robotic fish designed for experiments on collective animal behavior. The robot consists of two modules: a fish lure fixed on a magnetic base and a miniature mobile robot guiding the lure from below the experimental tank. In order to study the acceptance of the robot among living fish, we varied several parameters of the system and used design of experiments methods to reduce the number of performed experiments and determined the impact of each factor on the acceptance of the robot among a small group of real fish. While a brief comparison of the mean distance of the fish to the robot tends to indicate that the fish are attracted by the lure, a linear model of the acceptance of the robot is presented. Results of this study can be used to improve the design and control of the robot for further animal-robot interaction experiments