Funny you made this post today because just this morning (or maybe over the weekend) my redfin wrasse went through the overflow and into my sump. Funny thing is that I immediately knew something was up because although he's new to the tank (got him and a flame hawk at the same time about 3-4 weeks ago so Derek your post got my attention) he is almost always out front, so I checked behind the tank to see if he went "carpet surfing" and didn't see him. A little while later, one of my patients who is interested in salt tanks was looking at my sump and noticed him in there. I still haven't caught him. I think I'm gonna have to take the protein skimmer out to get him, so he's just hanging out for now. I might try using a soda bottle trap before I go to the trouble of taking out the skimmer. What a pain!
But I've had the tank for over 10 years and rarely if ever had any jumpers, even though the hood I had until last September was wide open in back. My new hood has two openings about 2"-3" wide where the pipes exit. I have a regular Mandarin who's been in there at least a year and a half, a flame angel (bout a year), two PJ Cards (probably 8 years) and new to the tank are the flame hawk, redfin wrasse and Diamond spotted Goby.