tubbylardo

That was my second guess, but I'm not sure why it would double in size over night. He might've aggravated it during the last water change, but I wasnt there to see. @Colu, papilloma being an external benign tumor? Would you stop dosing erythromycin, or dose both? And as for the nitrates and kh, unfortunately our tap water is very strange. GH is high, but there's basically no KH. And there's about 2ppm ammonia out of the tap. His nitrates are high because he did a water change. Normally the duckweed I gave him keeps that in check, but I guess it's taking awhile to process that. I can get him seachem alkaline buffer for the KH, that's what I use every so often for my tanks. But right now my main focus is saving the fish's eye if possible. Thanks for the replies everyone.

pH: ~6.8 Nitrates: ~100 Hardness: ~200 (florida water) Nitrite: 0 Ammonia: 0 KH buffer: 0 Temp: 70 F This is my friend's fancy goldfish, he's kept with a mystery snail in an under maintenanced 20 gallon. Sometime several months ago he bumped his eye against the walls of the old (10G) tank, and developed a small white growth above his eye. I convinced him to get a bigger tank, and told him to do more frequent water changes, and look into dosing erythromycin (my best guess based on how it looked). He never dosed the medicine, but did up his water change schedule. The growth didnt really get better, but it didnt get worse either. Two days ago he asked which medicine to get because he thought it looked a little worse (it looked the same to me), so I recommended erythromycin again. I told him to do a water change, then start dosing based on the instructions on the package. This morning, the infection is both larger and has spread ONTO his eye as well as above it. He's asking for advice, and beyond doing more medication rounds/water changes, I'm not sure what to tell him. The growth is mostly transparent/white, and looks bumpy rather than fuzzy.