I have a new 29 gallon tank that's been with tiger barbs for 2 weeks now. I just added two more last night (making 4 in the tank.... I read it's best to add to a new tank slowly which I'm still learning about). One of the fish has been swimming vertically since I got it home. It's the weirdest thing. I tried turning the filter off thinking it's a weak swimmer but he still spends 90% of his time with his nose pointing down. He does swim normally and very fast at times then suddenly goes into a headstand and flies around like that. Did a sick fish? Should I be worried? In case it makes a difference the new tiger barbs are the glofish kind.