Moving a betta

I'm embarrassed to say I never knew that bettas prefer a heated tank. We have a sweet little guy who's been living for at least the last 2 years in an unheated 3 gallon tank in one of my kid's bedrooms. He seems happy. He swims and flares his fins for us, and eats fairly well most of the time. I've noticed as the weather has cooled off and our house has cooled down, he's definitely eating less, and I'm wondering if that's related to the temperature.

Would we be better off getting him a heater, and if so are there any more reliable brands than others, or could he move into a small community tank? One of the kids has a 10 gallon with 5 neon tetras and a glowfish. (We lost some this summer during an extended power outage.) I've never put a male betta in a community tank, and I've read mixed comments about this. Would he eat the neons?

Thanks for any advice!

Thanks! I'll keep an eye on them and see how it goes.

Well, he immediately started chasing the neons. Big flares, lots of attitude. He definitely liked the space to move around though. Right now, I'm trying him in the 27 gallon barb tank. I've got 3 rosy barbs and 2 green barbs with flowy (how's that for technical?) fins, a Chinese algae eater, and a rainbow shark in there already. I was pretty worried about the barbs nipping the betta's fins, but he's been in there for about 3 hours and so far, I haven't seen any aggressive behavior from them. If anything, it's the betta I'm a little concerned about. He's not nipping anyone, but he sometimes darts after the other fish and flares. Considering he's been on his own for so long, I'm guessing this is just poor social skills? Does this sound like a decent transition? He's scoped out some hidey holes and the other guys are curious but acting normally.

Thank you so much for your input. I've been watching all day, and so far, so good. (And I totally agree 3 hours isn't long enough to be confident about anything.) I'd love to start a 10 g of his own, but that's not possible right now. His only options right now are his 3 gallon tank (and I'd definitely get him a heater) or this 29 g. We are in the process of getting a 37 g for one of the kids. We have the tank, heater, filter, lid, light, and air pump, but no gravel or plants yet. We're still planning out the fish for that one, but nowhere near ready to start cycling the tank.

It's been almost 7 hours now, (again, I know not long at all) and he's acting normally now as is everyone else. I hate to pull him out when it seems to be going well, but I'm nervous about how they'll do overnight. I'm home sick right now, so I can hang with them the rest of the day, but I'm not sure what I'll do tonight. The greens haven't tried anything yet, which is great, but also bad. If they acted up, then I'd know I was doing the right thing by pulling the betta back out. But they're behaving (for now) and he's happy in there.

Thanks for advice. I'll let him play while I'm up and pull him out before I go to bed.

Lol, I lied. I sent DH to the store for a small heater, and he came home with a ten gallon starter kit he found on clearance. Tank, lid, filter and light included.

Wanna know what it didn't come with? A heater.

Hubbie is on his way back to the store. LMAO