They are better than goldfish, about the same as guppys I think, not as good as mollies. If you have a place to salt quarantine them just go down to a small creek or pond and net out a load of gambusia mosquito fish, as good as guppys and unlikely to have elevated copper levels as well as free, your Rpbs will prefer that size for now anyway. By feeding the guppys,etc tropical color flakes and spirolina flake you load them with color enhancers and vitamins, your reds will also enjoy live small crickets and glass shrimp.