Fantail Goldfish Ammonia Problems

Question
Hi, I have a fantail goldfish and over the July 4th weekend we put him with another fantail goldfish in a bowl that can hold just over a gallon of water. We had just changed the water and thought it would be fine if we out them together for 3-4 days. When we came back on tuesday one of the fishes had a swollen face so I separated them immediately and changed the water. With each progressive day the fish with the swollen face has gotten worse. Initially he was swimming, now he stays on the bottom of the bowl and leans on his side. His fins have all shrank down. We usually change his water every week and feed him flakes 3 times a week. We even put him in a new bowl because we thought some of the ammonia from the other fish may be still lingering even though we changed the water. I have been diluting aquarium salt, only very little-1/4 tsp into his water but it hasn't helped. We think since he is not used to being around other fish he has a low immunity threshold.  What can I do to save him?

Answer
Aimee,

Each goldfish needs 20 gallons of water. 1 gallon of water is not enough water for any fish. Goldfish do not have stomachs and they are huge waste producers. In a 1 gallon tank, water changes need to be done daily or every other day. He was in very polluted water. Keep his water very clean and if the swelling does not go down, try Epson salts. This will help draw the fluid out of the fish. If kept in clean water he should be ok but it will take awhile to get him back to his healthy state.