any suggestions on easy to breed coldwater fish

[oranda man]

i am thinking about getting a 55gallon tank what easy to breed coldwater fish should i stock it with

[VoidParadigm]

Guppies and some other livebearers are okay at room temperature tanks.
Other coldwater fish like goldfish need three years to mature, and white cloud minnows usually don't eat all their eggs or babies so long as it's a species-only tank (meaning even scavengers/algae eaters are a no-no.)