Help! My goldfish has a hole under its fin!

[Copper]

My silver goldfish has a big hole under his fin! What is it? If its not curable, i'll have to do away with the small guy

 

[macky1]

has it always had it or does it look like a fresh puncture wound???

 

[ryan]

Is it a hole or somethine like a fish lice attached? It may have just damaged it or it could be Fin Rot or several other parasites, do you have a picture?