In this chapter, we focus on the use of robotic fish in animal behavior studies. Specifically, we describe the design and control of a low-cost robot along with accompanying enabling technologies for use in animal experiments. The robotic fish appearance and movement are inspired by the zebrafish animal model. The robot is capable of autonomous underwater operation. Two behavioral studies demonstrate the use of the robotic fish to test hypotheses on zebrafish social behavior. In the first study exploring zebrafish preference in a binary choice test, we find that the robot is able to elicit attraction in both individuals and small shoals when the other alternative is an empty compartment. At the same time, between conspecifics and the robot, zebrafish prefer the former, highlighting design choices that need further improvement. The second study describes the interaction between the robot and shoals of zebrafish in a free-swimming environment. The robot swims autonomously along predefined circular trajectories at three different speeds, corresponding to increasing tail-beat frequency. The robot is found to modulate zebrafish shoal cohesion, confirming expectations from the preference study result. In summary, the robotic fish platform described in this chapter provides a viable and fully controllable three-dimensional interactive tool for animal behavior experiments.