I had large wrasses escape though eggcrate. I don't know the mechanics of how that's possible but they got out. I guess it's not surprising because I swear those fish can swim through solid rock so why not eggcrate as well?! .... Seriously, either two possibilities: they fit through the squares; or they hit the eggcrate with enough force to lift it up enough for them to still pass overhead and then the eggcrate falls back into place afterwards ....
Sorry to hear of your losses... I love them wrasses to bits but it's so heartbreaking to find them on the floor.
