I feed mine Goldfish all the time. Goldfish are raised on pellets and flakes and rarely if ever have internal parasites. If they do, they are pretty obviously sick. I am not sure if fish parasites could transfer to a salamander but I suppose it is a possibility. I hand feed them to avoid fouling the water as Gold fish put on a lot of ammonia, scales and such when feed in the water. I would add also that you do not want to make Goldfish a staple as they are basically just fat. Greater for trying to fatten a tiger up, but usually that is not a problem.