The Order
Gymnotiformes
contains these Families:
145. Sternopygidae [glass knifefishes]
146. Rhamphichthyidae [sand knifefishes]
147. Hypopomidae [hypopomids]
148. Apteronotidae [ghost knifefishes]
149. Gymnotidae [naked-back knifefishes]
150. Electrophoridae [electric knifefishes]