Key to the subfamilies of Congridae

1a. Body extremely long and slender; pectoral and caudal fins reduced or absent; mouth short and oblique, lower jaw projecting beyond upper ............................................................................................................................................................ Heterocongrinae

1b. Body moderately stout to moderately slender; pectoral and caudal fins present; mouth horizontal, jaws equal or upper jaw projecting ........................................................................................................................................................................................................... 2

2a. Preanal length usually greater than 40% TL; caudal fin short and tip of tail stiff; posterior nostril below mid-eye level; dorsal-and anal-fin rays unsegmented; flange present on upper lip................................................................................................ Bathymyrinae

2b. Preanal length usually less than 40% TL; posterior nostril at or above mid-eye level; dorsal- and anal-fin rays segmented; flange on upper lip present or absent ............................................................................................................................................. Congrinae