Black Smudge

[lee8040]

we think our golfish has black smudge. is this contagious to other fish and how is it treated?

 

[Colin_T]

goldfish can develop black patches as part of their colouration. It can also be caused by chemical poisoning, the black being cell damage like bruising.

 

[black angel]

might be a healing patch due to ammonia burn... its a sign the fish is healing.