there is chasing and there is chasing
my Dovii will have the odd chase of a fish that gets near them or there bit of the tank
my GT will go out of its way to bother, chase and up-set fish he can, some of them when they was in the 4foot got stress RIGHT out by him
but yeah if you fish are doing fine with him keep it that way if your happy with it
"don't try and fix something thats not broken"