One of the goals of the ASSISIbf project is to create lures that can interact with zebrafish in an aquarium. These lures are ready now and are tested in 1m x 1m aquariums with 10 cm of water. The lure consist of a passive device placed in the water and moved by a robot placed under the aquarium. In respect to other similar devices, our robot is very compact. The length of the robot is 43 mm, the width 22 mm and the height 67 mm. The mass of the mobile robot is 80 grams. Moreover the robot does not need batteries, getting continuous power supply by brushes used to retrieve the power from conductive plates above and under the robot. This allows to run long time experiments with multiple robots. Preliminary experiments with zebrafish will be presented at the Robio 2014 conference in Bali, Indonesia.