I found a cyst

[ghettorigged]

I found a cyst on one of my Bloodfin tetras. It is near his tail and is rather large. What do I do?

 

[Bearfan]

Describe the "cyst". I'm not exactly sure which illness this would be, but I have a few ideas.

 

[ghettorigged]

it's a small, raised, cicular area near the tail. He still swims around looking for food but doesn't look like it's as easy as it was prior to the cyst.

I went and bought 10gallon tank today so I can put him in there if it is a communicable illness. What do you think it could be?