Tracking several objects from video recordings is a complicated image processing task but essential in many academic fields. We compiled a database of two-dimensional movies from very different biological and physical systems, spanning a wide range of scales and dynamics, and developed a general-purpose tracking software called FastTrack. It can handle a changing number of deformable objects. Furthermore, we introduce the probability of incursion, a new measure of a movie's trackability that does not require the ground truth trajectories. We demonstrated that FastTrack is orders of magnitudes faster than state-of-the-art tracking algorithms with a comparable tracking accuracy. A user and developer documentation is available, and the software is distributed under a GNU GPLv3 license.

Chemical perception mediates several essential behaviors in fish, like mating and feeding. However, there is much to understand on how the fish process chemical stimuli. We build two experimental setups: Dual, a high-throughput setup capable of assessing young zebrafish chemical preference, and The Tropical River to simulate realistic flows that fish are susceptible to encounter in nature. Dual is scalable, open-source, and can be built for less than 2 000 euros. Using it, we showed a clear repulsion to citric acid from fish up to 2 weeks old and showed that ATP's presentation to 2 weeks old fish was first repulsive and then attractive.