Black Ghost Knifefish (Apteronotus albifrons)

One of my favorite fish is the Black Ghost Knifefish (Apteronotus albifrons). It is just amazing to watch. To freely mix descriptive metaphors a Black Ghost Knifefish (or BGK) is matte velvet black with two white tail rings, and resembles a rippling curtain (the bottom fin is almost the length of its body) hanging off a curtain rod (the back/spine area) with its tail as the gently waving rudder. It has reflective eyes, a gaping mouth (although less gaping than a moray eel), is light sensitive and uses electrical signals and receptors in its head to navigate and find food. It likes caves, or cave-like structures, or any decor that makes it feel (electrically) secure. See my other post for current habitat and favorite foods.

The problem with many commercial aquarium decorations is that some have internal sharp edges which can severely damage this scaleless fish's body, even killing it. My second BGK, purchased a year after our first one died, somehow scraped "his" face damaging the electrical sensors. In spite of my efforts to hand feed him, he did not survive. After 6 months I decided to try again.

Wikipedia gives a nice summary, although my experiences with pH and temperature vary from what they suggest. In aquatic stores I have never seen BGK line up as the Wikipedia article suggests, in fact in they seem to avoid each other, with the larger ones chasing the smaller ones away. In store tanks with 3 or more BGK's, they are all hiding in separate locations.

The Wikipedia entry states: "The black ghost knifefish, Apteronotus albifrons, is a tropical fish belonging to the ghost knifefish family (Apteronotidae). They originate in South America in the Amazon Basin in Peru and from Venezuela through Paraguay in the Paraná Rivers. They are sometimes found in aquaria. The fish is all black except for two white rings on its tail. It moves mainly by undulating a long fin on its underside. It will grow to a maximum length of 20 inches (50 centimeters).

The black ghost knifefish natively lives in fast moving, sandy bottom creeks in a tropical climate. They prefer water with a 6.0 - 8.0 pH, a water hardness of 5.0 - 19.0 dGH, and a temperature range of 73-82 F (23-28 C). They are nocturnal, but they are weakly electric fish and use an electric organ and receptors distributed over the length of their body in order to find insect larvae.

Due to their electrical charge, a close, contained group of knife fish (as in an aquarium) will line up side by side."