I did think of the whole Large Fish+Small fish thing, but I really don't think a 4' grouami's mouth is going to be bi enough to eat a full grown schooling fish (rasbora,lemon,danios,)
Perhaps, if you find some small fishy that aren't babies, that aren't you know extremly small like some neons I see at the stores. And then get your gouramis at a young age, sort of like what you would do if you wanted angels and neons. That way by the time the gouramis are big the little fish will already be full grown 1"-1 1/2".
I think that would work.