Synanceja verrucosa, Inimicus filamentosus, Pterois volitans and Dendrochirus brachypterus slough permanently their outer keratinised layer of epidermis. In I. filamentosus and S. verrucosa this layer is formed by the distal segments of the epithelial cells, where in P. volitans and D. brachypterus the whole superficial cells are keratinised.
During the process of ripening the outer cells become loaded with fibrillar material and detached from the skin. In S. verrucosa several keratinised layers accumulate on the fish body and become invaded by algae and other fouling organisms. This produces an envelope of cryptic and protective value over the fish. As this ballast becomes too thick, the fish slough the cover, remaining protected only by the youngest sheet of keratin, attached to the superficial epithelial cells. The structure of the slough and outer epithelial layer resemble the “Oberhäutchen” described for squamate reptiles.
Teleosts Skin Sloughing Oberhäutchen Light and electron-microscopy