Yes, I've seen & heard of many other kinds of fish being kept with Goldfish, but I guess it's either hard on the goldfish (warmer temps) are hard on the other fish.
When I got my goldfish from my local petco & all their tanks filter through one another (except the saltwater tanks of course). So the goldfish were in a heated tank. So I floated them in their bag in my 20gallon heated tank for awhile & then put them in. I've been slowly lowering the tank temp a few degrees today & will continue to do so until I can take the heater out.
Since I already have over the goldfish stocking rule & a bit under the reagular fish rule, I will leave my 3 goldies to themselves.
I would consider adjusting tank temps if I had some kind of issue & needed to combine goldfish & other fish, but for now things will be left as they are. Maybe I'll switch my 75 gallon tank over to a goldfish & minnow tank in 5 years- but for now I'm enjoying my platies, mollies & corys in that tank.
Thanks for the replies & info.

Jen