We have a fish that had a lump on its side then last night it ruptured can we treat it with anything? It's in a small pond outside with one other fish. Both fish are about 11 years old. Thanks

I think this is the cause due to small pond size. The pond size is not sufficient for that both. About the fish that had a lump on its side is not a matter of worry, it will be okay by it self & if you want to treat with fish then please consult with a pet care (http://www.marinedepot.com/) expert.

Try melafix

How many gals is the pond or what are the dimensions? 2 gold fish are not too much, even for a small pond.