5 years ago, at my aunts house, i scooped up 2 brown bullhead catfish no longer then 2". 5 years later one is a little over a foot and the other is a little under a foot. My big one grew about 3-4" a year but then stopped at about 13". Could this be because they only grow to the size of their enviorment? They are currently in a 200 gallon pond with a spotted sunfish. If that is the case, what is the max size of this fish?