Island Frillfin

Bathygobius mystacium

The Island Frillfin, a member of the goby family, is found in the Western Atlantic, ranging from Florida and the Bahamas to the Antilles and down to Espírito Santo in Brazil. This tropical marine fish typically inhabits rocky tide pools and the edges of unsheltered shores. Divers might spot it in shallow waters, as it is rarely found deeper than 40 meters. The Island Frillfin can grow up to 15 cm in length and is characterized by its elongated body, 7 dorsal spines, and 9 dorsal soft rays. Notably, it has a variable pigmentation on its first dorsal fin, which may display 1-3 longitudinal stripes or appear uniformly dusky in larger specimens. The trunk features three dorsal saddles and a series of large blotches beneath the lateral midline. The Island Frillfin is harmless to humans and is currently listed as Least Concern by the IUCN. Divers encountering this species may observe its preference for staying close to the substrate, often among rocks and crevices. For those diving in its range, the Island Frillfin offers a glimpse into the diverse life of coastal fish communities. Its behavior and habitat make it an interesting subject for underwater observation, especially in areas with rocky substrates.