thought I'd share the experience I just had with my Yellow Coris Wrasse. Around 2 months ago I saw he disappeared from my Frag tank. He had made it to the sump but I didn't know it at that time. I drained the water from my tank and sump around 2-3 weeks ago and left the sump sit in the tank stand- no heater, circulation or anything. Then yesterday when I went to remove my sump to clean it out that's when I saw him swimming around. I was quite surprised and quickly caught him and got him into my nano, where he's doing fine. So in total he was 2 months in a sump and more impressively, 2-3 weeks in about 2 gallons of water, uncirculating and at room temp which ranged from appx 65-72. It's amazing how resilient some fish are!
I think you should name him "Diehard."
That's one tough fish.
Wow fish that won't die!! Fish sellers hate those kind.
;0
Ha...Ha.
And it eats vermetid snails! (and sadly trochus and stomatellas too)
He looks a little skinny but not that much. He was probably a little fat to start with and scavanged whatever he could find in the sump all the while avoiding the various pumps & plumbing hazards.
Best fish for controlling nuisance predators for zoanthids. Plus they're pretty reefsafe imo. Had mine with Shrimp and never bothered them and a work horse at non stop hunting.
Interesting thing for an ex-fish seller to say 
Bill make a key chain out of it
..................ok , ok , I am just kidding 
was he really skinny? I haven't seen mine in a while too....maybe I should check the sump.
Thanks,
Arnold