Five days ago I purchased a pair of Amphiprion ocellaris clowns, both about three weeks old according to the store. Acclimated, added to the tank. They seemed to be doing quite well, but today and yesterday one of the two is acting very lethargic and not eating (ignored flakes and frozen shrimp/scallop/seaweed cocktail). The other seems completely fine and ate the offered food, but sticks by the lazy one at the front-bottom of the tank. Here's the tank info:
reef, cycled and stable. These are the first fish.
Temp varies from about 78-80 over the course of 24 hr
<0.25 (hard to tell from the color chart)
These parameters are quite stable over time.
Is this normal clownfish behavior, or should I be worried? How long can they last without food, if this continues?
Perhaps coincidentally, the not-eating clownfish opens and closes its mouth constantly; much more frequently than the other one. Is this a typical variation in the species?