Yeah, I have a halfmoon who is very feisty. He flares all the time (especially in his larger tank). Sometimes he'll swim around the tank parading his flared fins. lol. I think he even flares sometimes when he wants to eat.
The sad thing is that I tried to put a mystery snail in his tank, but he attacked it and even though I moved the snail to another tank, the snail died a little over a week later. So, no tank mates for Fishie.
Fishie doesn't have any problems with the filter. I got the 5 gallon mini bow tank and I use the filter that comes with it and he doesn't have any problems swimming or getting sucked towards the intake. I think he likes chasing food pellets when they get caught in the current and shoot across the tank. hehe