It isn't clear how long you've had this fish and whether or not you use a quarantine system to verify the fish was healthy before you put it into your display tank. Being an anemonefish, it should also have been treated for Brooklynella as a precaution.
Sometimes an internally infected fish (bacteria or worms or parasites) will stop eating or slow its intake. But usually there are other signs, like loss of weight, and/or strange excrement. Strange excrement is usually not a result of the fish trying to settle in. Consider the possibilities by reading this short article:
http://www.petsforum.com/personal/trevor-jones/internalinfections.html
Another concern is when the fish is eating quite a bit of food, but doesnââ"šÂ¬Ã¢"žÂ¢t seem to gain weight. Where is the nutrition going? If it is the proper foods for this fish (see reference below) then there is a chance the fish is eating for ââ"šÂ¬Ã‹Å“twoââ"šÂ¬Ã¢"žÂ¢ or more (i.e., it has intestinal worms).
A fish with internal worms may live happily ever after or end up with the fuzzy end of the lollipop. The latter easily comes about through stress, poor water quality, and/or by not feeding the best possible diet.
For diet help, check this out:
http://www.reefcentral.com/forums/s...threadid=785228
If the fish isnââ"šÂ¬Ã¢"žÂ¢t eating then the only way to get medication inside of them is to put them in a quarantine tank and treat the water with chemicals that will kill the internal condition. The drug Praziquantel (a.k.a. droncit) will treat intestinal worms, Maracyn Two for Saltwater fish will treat an internal bacterial infection.
However, I'm not convinced it is a worm condition without more information. To be conservative, do an 80% water change and see if the fish seems to 'perk up.' If no response, treat the fish for worms, but also include an antibiotic that will cure an internal bacterial infection. If the fish definately perks up (starts eating or eats more), then check your water conditions including the source water and, if nothing is wrong there, treat you fish for an internal bacterial infection.
If the fish was fat and eating properly and being fed a proper diet (see above reference), with vitamin and fat supplements, it can live without eating for several weeks, providing all other environmental and water quality conditions are as they should be and the fish isnââ"šÂ¬Ã¢"žÂ¢t diseased. Praziquantel is best administered orally so see if you can get the fish eating.
:rollface: