Gold Fish Has Black Marks

[ClareJ]

Gold fish has black marks – black smudge?

Hi! I have two gold fish in a 60 litre tank. One gold fish is over 12 years old and, despite never being ill before, has suddenly started changing colour! He started with a black mark above his eye two weeks ago, which looks like a bruise, but now he has lots of black marks all over him. The other fish started having black spots this morning. The nearest explanation I can find is that it may be black smudge, but there doesn’t seem to be any information on how to treat it. I have been doing frequent 10% water changes, and water tests (which show a slightly high nitrate reading but nothing else unusual). Has anyone had the same problem with their fish? Any suggestions on how to stop the black marks spreading? Apart from the markings he seems healthy.

 

[black angel]

Can you get a pic?
Its unusual for it to be a colour change as fish in tanks dont usually turn black only in ponds.
It could be melanophore migration which you can look up using google.

 

[ClareJ]

Heres a photo of the black spots on my goldfish...

 

[black angel]

It looks natural to me especially on the fins. He has white also on the fins which suggest a calico background, maybe from a parent fish. Calico fish do have the pigment for black much stronger than other fish.
Keep an eye on your ammonia though and keep the water in good condition.
I wouldnt worry just now but if he gets more black then post more pics, he's pretty anyway.

 

[ClareJ]

Thank you for your help . I looked up melanophore migration and that seems to fit the description of what he has. Hopefully the black marks have stopped spreading - will be keeping a close eye on him