This system measures individual respiration in real-time in tiny organisms like Zebrafish embryos, Daphnia, fish/invert eggs or larvae, Drosophila etc., based on a 24-channel optical fluorescence oxygen reading device. Individual organism are placed inside gas-tight 80-1,700 µl glass chambers on a 24-well microplate footprint for real-time oxygen consumption rate measurements. Each chamber is fitted with a non-invasive and re-usable oxygen sensor spot that can be re-calibrated and sterilized for multiple trials. The microplate and reader is placed inside an incubator for temperature control, or use an optional flow-through water bath and refrigerated circulator. A soft silicone gasket with an optional line (e.g. parafilm) is placed on top of the microplate to seal the 24 chambers in one go. For high-throughput the system can be upgraded to include 10 readers/plates, i.e., for measuring respiration in 240 organisms simultaneously.