The Melanarus won't take too long to get 3+ inches. 250 is a big tank, and as long as the Mel has a SB to dive into he should be fine. Mine pretty much rules my 120, I would call him semi-aggressive, but the aggression appears to be secondary, he doesn't just chase the other fish around, but he does take after those that get in his way.
All in all a good fish, and I like having him because he is constantly reef-keeping.
