Hi.

The symptoms you are describing indicate a bacterial disease called Fin/Tail Rot combined with possible unfavorable water condtions.

My recommended treatment plan:

1) Change 30% of the water in the tank using dechlorinated water that is the same temperature as the water currently in the tank.

2) Add 1 teaspoon of aquarium salt per every 5 gallons of water. The salt will help prevent secondary infections from occuring and serves as a general tonic.

3) Slowly begin to lower the water temperature so that it falls in the range preferred for goldfish which is 62f-72f degrees. Goldfish are basically coldwater fish and will become stressed at high water temperatures thus lowering their immune system.

4) Begin to treat the fish with a medicine called Maracyn-Two which can be found at most major pet stores. Click on link below for a view and description of the product.

Follow the directions on the product label for usage/dosage instructions.

I know you mentioned that Melafix is currently being used but I've found that because it lacks pharmaceutical strength medicine it often does not effect a cure. It would be advisable to cease using it in this case.

Good luck on a speedy and full recovery for your goldfish and please let me know if you have any questions.

http://www.fosterandsmithaquatics.com/product/prod_display.cfm?pcatid=4842

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