i would just get rid of the catfish and go with the koi and a school of sunfish like longear sunfish. white sturgeon would be a bad idea because they get to be huge! just googlesearch teh thing and you will see what i mean.
i am going to wait and see exactly what kind of temps i get in the pond.
i will keep an eye on it all summer, and winter, and if i need to adjust temps up or down, i will