The melanarus is about just as nasty as the timor and earmuff in taking your your CUC crew from what i hear.
So its a pick between the melanarus vs timor vs earmuff as i heard they all grow up to simular sizes and have a nasty taste for hermit crabs.
But its fine... I don't really like hermits... i just get them when i need a filler on my reef cleaners order, and i try to restock on snails every 4-6 months. And if its a healthy snack for the wrassee, then so be it.
Oh but if you do add a Halichores, if you ever get aptasia... you can never use Berghia, unless you want to feed your wrasse a A4 grade flatworm wagyu.