The teeth project forward from the jaws and are used to seize and crush molluscs, crustaceans and echinoderms. Their blue colour is visible in live fish and in fresh specimens and is not an artefact of lighting or a coating of algae. It appears to be a property of the mineralised tissue.
Blue and green in tooth or bone tissue is very rare in vertebrates. A better-documented case is the blue-green fluorescent bone of the chameleon genus Calumma and the green bones of certain garfish and needlefish, which owe their colour to biliverdin, a bile pigment. Whether the tuskfish's tooth colour arises from a comparable pigment, from structural effects in the enamel, or from something else has not been established in published work that is easy to point to.
The related Australian blackspot tuskfish is separately notable as one of the first fish recorded apparently using a tool: individuals have been filmed carrying a clam to a rock and smashing it against the surface repeatedly to open it, behaviour that persists across sites and individuals.