When i had my 200 I lost clownfish, large purple tang, blue spot jawfish. The culprit was a very large rock crab, I finally found his home and removed him. The only thing I every found was a small piece of jawfish which led me to his home. It is amazing what nocturnal items lurk in our tanks? Hopefully your fish will come back out during the day. If you look back at my post on the yellow head jawfish one of mine took a month to come out during the day. I believe he was use to hunting for food which the tank had a bunch of mysid shrimp which move at night so the jawfish kept that routine until he ran out of mysid and had to come out during the day to feed?