I think the reason it ended up in there was bec my filter sock was clogged, so the overflow wasn't draining at all. I noticed it missing last night but thought it had just gone to bed early....
might have just swam on in.
I do need to cover the tank as its not just wrasses that jump, I've lost clowns, hogfish and even my trigger jumped (I was sitting in the room when that happened and was able to toss him back in)