goldfish ailments

[DebDeb]

My goldfish has got some black stuff on its tail.A friend who has got fish said not to worry but you can see it is risen and it has spread.It is in an aquarium and has lived on it's own for a few years now .It's about 6 years old .Now I have noticed what looks like a growth os something embedded in the scales.I do buy oxygenating plant but I always rinse it before putting it in the tank.I have two goldfish books and can'd find out what it is in them,nothing black.I am not confident in holding the fish to treat it either as it is quite big.Is there anywhere I can take it .It looks really happy otherwise but I don't want it to get worse or get ill.Anyone know what it is please?

[B00]

See if any of these match your poor goldies ailments.

http://www.kokosgoldfish.com/disease.html

[tiger~torah]

it could be some kind of fungal infection, brought on by water type etc.
hope this helps

[DebDeb]

Thanks I will have a look at this site and hope I can sort it out
Thanks