Black Ghosts are one of the most fascinating, fun fish I have ever owned. I currently have one that's 3-4" (maybe a little more), and it's like having a pet dog, personality-wise. I swear, if I drop one single freeze-dried bloodworm in the tank, he jolts out of his pvc pipe, and starts scanning the top of the tank in a vertical sprint... It's absolutely hilarious. Lately i've been hand-feeding him small pieces of earthworms - I try not to do it too often, I want his diet to mainly be the bloodworms, with the earthworms as a treat, because if I have my Striped Peacock
and my Black Ghost eating worms, it could get a bit pricey.
I'm going to have to back up benzjamin13 as far as being territorial. He's calmed down quite a bit in the last couple of weeks, but when his friend the Peacock Eel (unagi - yes, they're friends) would try to crash in, or behind his pvc pipe, my Ghost would be like "uh-uh... *nip*" my Eel would just be like "Come on... Really?!"
They're both able to stay in or around it now though.