When I brought my Bartlett's Anthias home on Friday night, one disappeared for the day, the other two were instantly swimming around in the current with my clownfish like they were all one happy school.

Saturday, all three were out, and swimming around contentedly every time I went over by the tank.

Today? Only two were swimming around. I noticed the third was perched in an overhang, and he was upside down. The cleaner shrimp went over to him and cleaned out his mouth, then the Anthias seemed to get annoyed, and swam out in the current with the other three for a few minutes, then was gone again. And, again, upside down in the cave.

He swims just fine -- when he wants to. And he's presently hiding again in the cave, but now he's right side up.

I know they're shy fish, so I wasn't too concerned that he went hiding the first night; but is hanging upside down in caves normal behavior? I've never seen a fish do this before. I haven't noticed any signs of illness on him, and I've seen fish with broken/punctured swim bladders before and he's not behaving like that. He's otherwise eating, and swimming well, and I'm guessing he's just taking some time to adapt to the aquarium, but I'd like some confirmation.