Strange clownfish behaviour
I have 2 small false percula clowns (ocellaris) that are showing some pretty strange behaviour.
First off, they are not eating. They were the first fish introduced (a month ago) and they used to eat a lot. I mean a lot, and all kinds of foods. In the last week or so they never "fight" for food and they don't bite even if a chunk of something is floating just before their eyes.
Other fishes in the tank are as follows: 2 very tiny perideraion clowns (no fights or problems whatsoever with the false percula), 1 canthigaster (puffer, the big eater), 1 pretty large hepatus (blue tang).
I was already worried about this when today they started to look interested in a little amphora jar I placed in the tank long ago. This was a first. The bigger one entered it and stayed in there all day (making me seriously think it died, since I can't see the inside), while the smallest swimmed around very far from it, getting in only on occasion. At some point, and more than once, he had what looked like a very thin white thread hanging from him, bottom side just behind the fin. I thought it might have been sperm, but he didn't "use" it in any way. On one occasion it eventually detached and the blue tang ate it promptly. Hm.
I can't see what the larger clown is doing in the jar without moving and twisting it and I don't plan to do so.
The fish seem healthy otherwise. They are now sleeping very close to the surface as they have always done.
Can someone please explain this? And how can I get them to eat again?