A lot of people say no, but I say yes. I have six in my tank that I got about a year and a half ago, and all six are still in there happy as can be. Yes, they need heated water, but if you have egg shaped goldfish, that's good. I believe it's a misconception that "goldfish shouldn't be in heated tanks." Maybe that's true with some of the more common varieties, but the fancier egg shaped varities do better in 74-76 degree water. Mine are pretty big and the goldfish show no interest in trying to eat the frogs. My frogs can swim directly in front of my goldfish's mouths and the goldfish just turn their heads away.