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 and "S. fluitans") have become holopelagic—reproducing vegetatively and never attaching to the seafloor during their lifecycles. The Atlantic Ocean's Sargasso Sea was named after the algae, as it hosts a large amount of "Sargassum". "Sargassum" was named by the Portuguese sailors who found it in the Sargasso Sea after the wooly rock rose ("Halimium lasianthum") that grew in their water wells at home, and that was called "sargaço" in Portuguese (). The Florida Keys and its smaller islands are well known for their high levels of "Sargassum" covering their shores. Gulfweed was observed by Columbus. Although it was formerly thought