sick black moor

Question
My black moor recently developed a blister of sorts above his right eye. Today I noticed it had burst, and now there is a white substance coming out of it. Any idea what it is, and should I try squeezing the rest out? Will it infect my other fish?

Answer
Hi there, sorry to hear the bad news!

I think I would leave the blister alone. Change 50% of the water everyday to help reduce the risk of infection caused by dirty water getting into the open wound and overall just making things worse. And I'd add some aquarium salt (pre-dissolve it first) to the aquarium.

How is the goldfish behaving?

Unfortunately it is very difficult to diagnose fish illnesses such as these without being able to see the fish and even then it may be difficult unless we can look at a sample under a microscope to determine the pathogen.
It may in fact be a bacterial infection. Could you isolate him to his own tank? I would try treating with a good antibiotic. Feeding him an antibiotic food would actually be a lot more effective than treating the water but I do know that some fish downright refuse medicated food and water treatment is then necessary.

You might want to look here on this site (scroll down on the web page) for the part about sores and other illnesses goldfish can develop.

http://thegab.org/Articles/DiagnosisChart.html#sores

Best of luck and I do hope this helps!
Karen~