This morning I was watching Beau doing his usual "flirt for food" routine when I noticed something a little worrying. His tail, which was full and unharmed yesterday has a fairly long rip in it. The only new item in his tank (which I've removed just in case) is a leaf hammock. The first thing I did when I opened it was remove the wire, so I know that's not the cause.
He's still swimming around the tank normally, and he doesn't seem stressed. He does keep flaring at me, but I think he's still upset with me for leaving him alone all of Saturday and most of yesterday.