When to know about goldfish diseases occur. Not much time constant occurs at temperatures around the time just now and spring. Will always be sick if they breed goldfish in dirty water and water changes of course neglect. Ich is the most common diseases of goldfish. White spot disease has become worse and definitely no longer healthy complexion even my goldfish.
If you find there are signs of such, there is not addressed immediately! The situation will become irreversibly spread between said.
Action is very easy to say that. If I put the fish in salt water tea. If the tank 60 cm, and the first water change of about one cup of halving the water cup, "you storm" to put. Solve two or three days to put goldfish in it. Did not give food, no filtration. Then most likely would have healed.