Gold fish problem

[Vnewbury]

Daughter's goldfish developed a couple of swollen scales. Didn't think too much of it as he doesn't appear sick, eats well, interacts with other 2 gold fish in the tank. Now one of the swollen scales has turned black. He continues to act as if he is fine. We've had him for about 7 years and are quite attached to him and would hate to lose him. Thank you for any advice or knowledge you can share.

[Dme071279]

Have you tested your ammonia levels? Could be from the ammonia being a bit high. Also may be a sign of some sort of parasite.

[DrWho42]

oh no! hope they get better

[Port Captain]

Gold fish are dirty fish and need constant water changes. At least 10% weekly. 1 goldfish needs about 20 gals of water, a second gold fish would need and additional 10 gals. Small tank will need more water changes then a larger tank. Usually the black is an ammonia burn caused by dirty water ( needs 50% changed). I have a fancy tail goldfish in a 50 gal tank and do a 10% change weekly. If I miss a week or 2 the goldfish gets stressed and sits at the bottom of the tank. I do a 10% change and the next day its swimming around happily. Good Luck! I know the pain.

[Mother of fish]

Welcome! Could be tumors or a cyst?