No aggression from betta?

[Garlisk]

Hey folks, I have 2 betta in tanks next to eachother. I normally keep a piece of paper between the tanks so they cannot see one another, but every now and then I remove the paper because I've heard they like to puff up at eachother and go nuts for a little bit.

I recently noticed, however, that one of my fish doesn't care. The one will puff up and dart around, but the other will continue swimming around as if nothing is going on. When I was in the pet store, I "tested" him by putting him next to another fish and he puffed at it, so I'm not sure why he wouldn't be now?

Should I be concerned that perhaps he isn't happy, or something is wrong? He looks fine and is eating fine. He can see, because when I come to the tanks he tends to swim to the front and watch me (which is good fun.)

Any info would be nice, thanks!

[RillC]

Actually, my two fish are exactly the same. One goes nuts with the flaring while the other is more like just swimming around and teasing the other. Perhaps, as with my boys, the one that doesn't flare as much is quite a bit smaller/ younger than the one that flares? The non-flaring one is a zippy little perpetual motion machine otherwise, happily building bubblenests and begging for more food.

[Myates]

Yup.. I have one like that too. He'll flare when next to a female, but not another male. You just have a calm one :)