Nooo it's not heated. I keep my apartment about that warm. I also have a versa top on the tank, so that probably keeps some heat in.
With my sunfish, I feed every other day. But they eat cichlid pellets and one likes to eat too much.
I have tropicals that get fasted one day a week and a betta who actually DOES bloat very easily.
Two days ago, one of the mudminnows stole a worm from another and ate it. 4 red worms she shoved down her gut until I started shoo-ing her with a skewer. She had a hard time swimming for a while, but was begging the next day.
Two are about 5 inches long and the smaller one is 4-ish. I tried to measure them, but the ruler scared them. They're big enough to eat their mosquitofish tankmates, which is why I'm re-doing my 55g for them.
EDIT: The mudminnows are in a 20g long with 4 mosquitofish and 3 of what I think are bluntnose minnows. Basically, it's my bait fish and feeder fish finds.