I kept tropical aquariums as a child and, out of misplaced love, I killed ever so many poor little fish (I still have frequent anxiety dreams about my past mistakes).  My favorite of those hapless fish friends was a black ghost knife fish (Apteronotus albifrons).  Here’s a picture, but it doesn’t do the fish justice (because it’s hard to photograph things that are all black):

My black ghost knife fish, Ripley, was a fascinating character who would freeze into the shape of sword plant leaves and sway in the current to fool prey.  Ripley was an uncommonly gregarious fish who would always swim up to the front and show off for his (her?) favorite people when they entered the room.  During feeding time, Ripley would eat out of my hand and even lie across my palm.  He also liked to play in the bubble stream from the aerator and “surf” the water stream from the filter.

According to the redoubtable ichthyologist, Herbert Axelrod, Amazon tribal people believe ghost knife fish to be returned spirits of  dead ancestors and do not molest the fish.   Although I never heard a tribesman confirm this,  the fish do indeed look most ethereal.  Ghost knife fish hunt by reading/sensing electrical fields and they can emit an electric shock to fish who nip at their vermiform tail.  Because their almost vestigial eyes are not their foremost sense (and thanks to the remarkable fin which stretches down the length of their body), they like to swim backwards.

Although these fish can be bred in captivity, successful pairings are very rare.  Evidently Ripley was captured in the Amazon basin and shipped to the pet store where my little sister purchased him as a birthday present!  He lived in my community tank and one day I was trying to heal another fish’s fin rot so that it wouldn’t spread to Ripley.  But the medicine killed him.  Gah!  Rest ye in peace Ripley! You were the most likable fish I have ever known…