Hi Savannah,
The reason for not using goldfish as a food item is that they contain the enzyme Thiaminase (see the link).
http://www.thamnophis.com/caresheets...?title=Thiamin,
One or two, occasionally, is probably going to do no harm, but as there are so many readily available alternatives, I would personally recommend that you avoid them altogether. If your snake will take fish pieces, you're on a winner straight away, trout is good and easy to buy. If not you could start it off on Rosies and then gradually wean it onto frozen/thawed fish pices. Good luck. If you want more info just ask.
