Its toponomy was first defined by Father Gaspar Frutuoso during the 16th century, who reflected on the fact that the area received its name owing to the physical topography. As he indicated, the terrestrial physiography, and specifically the land around one of its bays resembled a "fish tail", or in Portuguese "rabo de peixe" (literally "tail of the fish"). Similarly, another reference by the priest and chronicler indicated that the area was also known for the discovery of the tail of a large unknown species of fish, and may have received its name from this legendary account.