Alright, I recently (2 days ago) got a third betta (link to post with pics of new guy; http://www.bettafish.com/showthread.php?t=114462
I figured he would do just fine in my 20 gallon community tropical tank.
That is stocked with
1x Black Balloon Molly (she's not even an inch long with her tail)
1x Copper Marble Sailfin Balloon Molly (He's completely full grown)
1x White Molly
2x Glass Catfish (yes, I know they need to be in larger groups, however, these two have outlived every other glass cat I've had and they are perfectly fine in their pair)
And thats it. I might get a wrestling halfbeak to go in there, maybe. It's not overstocked, I still have plenty of room for a betta.
So, I put Mr. Simon in the 20, and he couldn't even swim the direction he wanted to go. I forgot to take into account the filter current and what he'd be able to swim against with that big 'ol double tail and his giant fins. And then, instead of him picking on everyone else, everyone else decided he was food and started kinda like, going close to him to check him out and he apparently doesn't like other fish because he would freak out and swim in a crazy circle and then go sit on the bottom every time someone came close to him. Then he discovered the glass cat's cave, kicked them out, and was sitting in the entrance so no one could get in. Which was fine, the glass cats have other hidey holes. SO, needless to say, I put him in his cup again and floated him on the top of my other 5 gallon betta tank that houses Bleu (CT) and Calvin (VT). I took Calvin out and floated him on the 20 gallon in his cup. He is a MUCH better swimmer than the other two and does quite well for a betta against the current. He never really struggles. After about 15 minutes, I let them both free. Simon (new guy) REALLY likes the low current 5 gallon. Calvin seems OK in the 20, but he's stalking the other fish. He gets really low to the gravel, then pounces on anyone that swims by. I'm sitting in a chair facing both the tanks watching them carefully. Calvin is swimming great in the 20 and doesn't seem to be attacking everyone as much as he was at first.
Then we come to the Bleu problem. He's furious I took Calvin away. Like, will not stop half flaring at me, is flaring at Simon through the divider, is darting around, flaring at the thermometer, flaring at the heater, flaring at the plants. He's throwing a temper tantrum.
So I'm wondering if it would be a good idea to set up my 3 gallon, put Simon in there, and then put Calvin back in his tank so fussyface Bleu can stop flaring at everything and stressing himself out.