RECENT FISH OTOLITHS The fish otoliths are situated in the head, and allow them in particular to be well situated in their environment. They have three pairs of them, but the only one is of sufficient size to be found. They are formed by calcite, every day a very fine layer settles above. This explains that they are not completely similar from a fish to other one for the same species, according to its age. Each species has its own shape otoliths. It is a criterion of identification (that we