If you prefer to not heat the tank above ambient temperature but it's at least in the low 70's, you may wish to consider red phantom tetras also. There aren't many fish which do well in this middlin' zone which can be in a 10 as Froggy said, you've pretty much covered it. Some barbs, i.e., rosy barbs, also do fine in cooler tanks.
Mikety> a 5 gallon is not ok for a goldfish. I use an 18 just to quarantine.
__________________ Tanks everywhere, a well-stocked garden pond outside and a Horde of Flatcoated Retrievers  |