Micro computed tomography (μCT) provides a non–invasive approach of inspecting internal structures in organisms. In this study, μCT is being used to investigate the relative density in the jaws of a potamodromous piscivore. Samples are scanned together with hydroxylapatite phantoms—which have known density. Using the phantoms, a calibration curve is created by relating pixel intensity of the phantom image to the known density. Using the calibration curve, the pixel intensity of the sample image is then converted to relative bone density. The differences in relative density between specimen is currently being assessed. This study aims at establishing use of μCT in ecological studies as a non-invasive tool for studying fish populations.