Question
We just yesterday bought two shubunkins and a goldfish to add to the three we already had in our outdoor pond. The goldfish's mouth appears to be slightly swollen (in comparison to the others) and is white in colour. He also appears to have a white hair coming from either end of his mouth, (like a catfish almost) and his lower back fin has white along the bottom.
I don't think it can be fungal because:
1) We treated our pond with a fungicide because one of the first fish we bought was affected with some kind of fungus(it died)
2) The place we bought the fish from was also treating their water as they had an outbreak of the same disease our first fish died of.

I did think possibly Columnaris, or mouth rot. The whiteness doesn't appear fluffy but the mouth looks abnormal. We weren't able to get near it with a net in order to look closer, but the whiteness looks bigger than it did yesterday. The skin of the mouth isn't smooth either, sort of bitty perhaps like it is rotting?

However, it does seem healthy - is swimming happily, not isolating itself, eating food. There are no ulcers or anything like that and doesn't seem in any way unhealthy.

I would much appreciate your opinion. It could of course be normal, like a difference in appearance because of gender for example, but being no experienced fish keeper I thought it wise to check it out. I also don't want any more to die.

Thankyou for you time.

Answer
Hey Catherine, its sounds like some fungal mouth disease to me. I would start getting my fish somewhere else. Seems they are having some trouble with there fish. If you can't do that then you need to get a holding tank and keep them in it for a couple of weeks to see if they get sick. I have salt water fish also and I always do this. Or sometimes I will pick a fish out then leave it at the pet store to see if it gets sick for the next couple of weeks. They are to expensive not to. Thanks Eric