Additional information (Wiki):

Black ghost knifefishes require a large tank of at least 208 L (55 US gal), and should be provided with a shelter (such as a plastic tube) in which to hide. They will eat smaller fish in the tank and are intolerant of conspecifics. As with other scaleless fish, they are vulnerable to parasite infestations such as ich (Ichthyophthirius multifiliis). Reports of successful captive breeding are tenuous.