Symphurus is a genus of tonguefishes found in the Atlantic, Indian, and Pacific Oceans. Most species mainly occur in relatively shallow water, including estuaries. Some species are also found in deeper water, including S. thermophilus that lives at hydrothermal vents (the only flatfish known from this habitat).Symphurus species are distinguished by merged dorsal, caudal, and anal fins, the absence of a lateral line and pectoral fins, and the presence of only one pelvic fin.