I have one of these strange banjo guys.
He's a boring fish. Most of the time he is buried in the sand.

Upon researching the Banjo, (after i bought him) I learned that when they are adults they may become carnivorous and eat other fish during the night..
When i purchased him he was about 3 inches long, so I imagine he is pretty old...
None of my fish have disappeared, but I'm nervous, wondering if anyone has experienced banjos eating their tank mates.