plural of knifefish

Any of numerous fish with knife-shaped bodies, from several different families.

plural of ghost knifefish

Any of the family Apteronotidae of ray-finned fishes in the order Gymnotiformes.

Apteronotus albifrons, a tropical fish of South America, black all over except for two white rings on its tail and a white blaze on its nose, occasionally extending into a stripe down the back.