Originally Posted by tanker
Columnaris might be a possibility. Or a fungus. I've no experience with diagnosis or treatment, so wait for someone knowledgeable to help you with that.
As for prevention in the future, can you post some more information about your tank? How big it is, whether it is cycled, how long it's been set up. Have you been testing your water for ammonia, nitrite and nitrate levels? What's your water change schedule? How long have you had your fish? If you give some more information, the people who can help you will have more to go on.
Sorry about your fish.
I have a 10 gallon tank with around 2 inches of gravel. I have a cave and a few fake plants. A tetra whisper 30 filter, aqua 30 air pump. i have 2 fish, one shubunkin and one commet. my tank is around 2 weeks old, about to do a water change soon, and I have no idea what "cycle" even is.
As I said I am a newbie and would love to give my fish a good home. nearest pet store is around 30 min away, all i have close is a walmart.
There are a few pics on my album page. I like all remarks and criticism :p
All help and advice is greatly appreciated.