HI MIKE P. , WELCOME TO FISHLORE.
I think the first thing I am going to suggest is that you go to the "ARTICLES" up at the top of the page. Read everything on setting up a beginning freshwater tank, the nitrogen cycle, and then look under fish profiles.
You will see that goldfish need to be in a much bigger tank than you have, so you may wish to re-think the kind of tank you keep.
Tropical fish and gold fish have to be kept at different temperatures, so really aren't suited to be kept together. There is a lot of reading there, but it is a good place to start..