[Betta splendens]

Yesterday I got two goldfish for my large aquarium (forget the gal. ammount, but its big enough for two Sarasa comet goldfish, and yes I know how big they get).

What bottom dwellers can join them? Would crayfish harm them, or would they when the fish get bigger?

I'd like to mainly stick to cold water, so corys and plecs are out. And I'd rather no catfish.

I'm thinking of a spinned loach or two, as they're found in local streams, but are there any suggestions?

Thanks