Sargassum fish are present; the gills open as pores near the base of the pectoral fins. The anal fin has no spines and seven to 13 soft rays. The pelvic fins are large and the pectoral fins have 9-11 rays and are stalked and able to grip objects. The outer rays of the tail fin are simple, but the central rays are forked. The sargassum fish has a cosmopolitan distribution in tropical and subtropical seas down to a depth around . It is found in parts of the Atlantic Ocean and the Indo-Pacific Ocean, where drifting seaweed accumulates. In the western Atlantic,
Sargassum muticum Isle of Wight in 1973). Currently, the alga is widespreaded from Norway to Portugal along Atlantic's coasts. "Sargassum muticum" has a range stretching from Campbell river, British Columbia to Baja in California. In Europe it extends along the coasts of Great Britain, France, Scandinavia, Baltic Sea, Helgoland, Netherlands, Ireland, the Iberian Peninsula and into the Mediterranean from Italy and the Adriatic. It is recorded from Japan, China and Alaska. Recently, some specimens were found on Moroccan coasts. It illustrates its huge tolerance regarding to its environments. Herbarium specimens are now stored in the Ulster Museum (BEL catalogue numbers: F11241 -