Hello. My tank has been set up about 6 months now, and I had gotten a YWG that has been in the tank about 3 mos. He always came right up to the glass when he saw a person. About 2 wks ago I added a firefish who shared his cave, and now it's been about 4 days since I've seen him. I am very upset about this, he is Mr. Personality in my tank. I have not recovered a body. Is this normal for the fish to 'disappear' or something else? Thanks