Yeah, what's up with that? My midas got darker too. Only his tail is yellow.Nice tank. I miss my yellow midas blenny (turned blue/purple because he was apparently bored). As for the Yellow Devil damsel, I want to make sure I'm not confusing it with the Azure damsel.
I had a Yellow Belly damsel that was a complete ***hole, so it sounds it sounds like we might be talking about the same fish here. Mine dug up the sand bed every chance he got, and would even swim over and dig it up again right after I filled any holes.
I had a yellowtail damsel that used to nip corals. I finally got him with a blast of air from my pellet rifle.