The predatory mesopelagic fishes Borostomias panamensis and Stomias boa (Stomiidae) have typical sharp long fangs. The cross section of their teeth shows that the dentinous wall of the pulp cavity is smooth, contrary to the pleated wall found in several predatory fishes like e.g., Hoplias aimara (Erythrinidae), Anarhichas denticulatus (Anarhichadidae) or Lophius piscatorius (Lophiidae). Therewith, B. panamensis and S. boa lack the plicidentine layer in their teeth. We further confirm the acellular nature of the bone in Stomiidae, already signalled in 1859 by Kölliker for Chauliodus.