Hi. I've a poorly goldfish! I've filled in the details below to the best of my ability and also included a photo Test Results for the Following: * Ammonia Level - Unknown * Nitrite Level - Unknown * Nitrate level - Unknown * Ph Level, Tank (If possible, KH, GH and chloramines) - Unknown * Ph Level, Tap (If possible, KH, GH and chloramines) - Unknown Other Required Info: * Brand of test-kit used and whether strips or drops? - Not used * Water temperature? - * Tank size (how many gals.) and how long has it been running? 30 Litre * What is the name and "size of the filter"(s)? - Unknown but it's a biOrb 30 * How often do you change the water and how much? - Approximately once per month and refill the entire tank * How many days ago was the last water change and how much did you change? - 7 days, 25% changed * How many fish in the tank and their size? 1 x 13 year old fish, approximately 10cm in length from head to body - not including tail fin * What kind of water additives or conditioners? - Not used * What do you feed your fish and how often? - Daily, 5 flakes of Aquarian Advanced Nutrition Goldfish Flake Food * Any new fish added to the tank? No * Any medications added to the tank? Yes, Melafix 3.5ml daily. Been using for 3 weeks * List entire medication/treatment history for fish and tank. Please include salt, Prazi, PP, etc and the approximate time and duration of treatment. - See above * Any unusual findings on the fish such as "grains of salt," bloody streaks, frayed fins or fungus? - Fungus at rear of body and top of body, as seen in photo below. * Any unusual behavior like staying at the bottom, not eating, etc.? No, all is normal with the obvious exception of the fungus. Around 3 weeks ago we started treating the fish with Melafix. We first noticed the fungus around 4 weeks previous to treatment. It started turning grey in the centre of the white fungus which now appears to have gone but the fungus remains. Any help would be greatly appreciated.