It is probably worth mentioning that this fish, either the red tail black shark or the albino form, needs a 4-foot long tank. It also has an often nasty disposition, and other substrate fish can be pestered to say the least and even killed.
Yep, they can get really mean as they get older, and not just to the substrate fish. Mine was perfectly well-behaved until he got about 3-4 inches long. Then he started terrorizing the entire tank, even the top-dwellers, and had to be removed. They are one of the most striking fish in the hobby and well worth keeping, but you need to have a plan for rehoming. Or just keep it by itself.