I've actually seen 15" orandas. They sell large ones at the crappy store I once wrote a thread about. They want $80 for one so I didn't get too tempted. He also wouldn't sell the one with deformities due to TB. Fortunately it takes a long long long time for the round goldies to get that big, if ever. Three will enjoy that tank for years.

I also mix tropicals and goldfish . Once you've had a lot of experience with fish, there's no problems mixing the two as long as they are species compatible. I'd never mix livebearers with goldfish. I have Depot, my comet, in with my tetra tank. Goldfish being strictly cold water and trops being strictly warm water is just a myth (perpetuated by fish lovers who want newbies to take things slowly).