Ophichthys is a genus of swamp eels (family Synbranchidae) native to South Asia, with the three atlas species - the Gangetic mudeel (O. cuchia), the Malabar swamp eel (O. fossorius), and O. hodgarti - found across the plains and wetlands of India, Bangladesh, Myanmar, Nepal, Pakistan, and Thailand. Like other synbranchids, they have a long, eel-like body with no pectoral or pelvic fins, a single small gill opening, and a vascularized chamber that lets them gulp air at the surface - an adaptation that allows them to survive in stagnant, oxygen-poor ponds, rice paddies, and mud burrows through dry-season drawdowns. A population has also become established in the United States, most likely through aquarium or food-trade releases rather than a natural range extension.
Swamp eels of this genus are a minor presence in the aquarium hobby, kept mostly by specialist oddball and eel enthusiasts rather than sold as mainstream stock; they are hardy air-breathers that tolerate poor water quality but are predatory, secretive, and given to burrowing, so they suit a dedicated low-light tank with a soft substrate rather than a community setup. They are more significant as food fish and as a subject of academic interest in South Asian wetland ecology than as ornamentals. Of the three atlas species, one carries an IUCN assessment of Endangered, a reminder that wetland drainage and conversion to agriculture across the Gangetic plain put real pressure on species that depend on seasonal marshes and paddy systems even where they are still locally common.