Tilapia grow faster but if your in colder climate it might be less heating. I’m in SC so heat is more an issue but I run lines underground to cool water. Tilapia also grow well on duck weed which I can grow in one tank so my feed bill is nil.
Prolly gonna start with perch till I figure out what I am doing - My buddy in CO uses passive solar to heat the water tanks in order to help heat the greenhouse - and I am going to try something similar... I will probably still need a coal/wood stove in it for the bitter cold, but I am not going to get year-round anyhoo. Most likely going to have to shut it down in January, which is fine, as I can get my starts going in late feb that way... Production is pretty grim late winter around here anyway.