Fantail Calico Goldfish appears sick

Question
Benny, My Fantail, appears to be sick. He is very lethargic and often times just lays on the bottom of the tank and looks very tired. He looks healthy, other than his stomach looks a little larger than normal. I have had him the longest of all my fish. I have had 2 fish die recently, one just today and I am very scared im gonna lose Benny. My other fish was a fish from wal-mart (a smaller fantail) and we tried to nurse him but it was fruitless. But back to benny, He swims to the top and eats but otherwise he just sits at the bottom of the tank and breaths. If I come and peer into the glass, he will swim out and look at me and then swim around before going back into his treasure chest and lying down. I have checked the water and everything seems fine/normal. The PH/Alkalalinity/Ammonia/ etc. is all fine. What's wrong with Benny... am I gonna lose him? I am still depressed that I lost Peko today... I plan to take him and a cup of water to the store and have them test it. Please help me if you can!!!!

Answer
Hello Matt-

I don't think you should move Benny anywhere; it would cause him a lot of stress. Instead, try to do a 50% water change with Benny in the tank. Rinse off the parts of the filter, and make sure it is working properly. If the filter is not making enough bubbles, try getting a bubbler to agitate the water and get more oxygen dissolved in the water. Make sure his water is not too hot (should be mid 60's to low 70's) You can also try adding a dose of aquarium salt to the water or a dose of Melafix.

Are there any symptoms he is showing (ex. white spots, fuzz, sores, etc?)

Hope this helps,
Amber Worman