My Grandfather, now deceased, was a breeder of terrapins for over 39 years. All of his babies were raised in freshwater. I don’t really think it matters. I have raised some in saltwater and most in freshwater. All about the same growth if you ask me. The only difference I can see is that a terrapin raised in saltwater has a “rougher look” than a terrapin raised in freshwater. Like I was saying, I just think it depends on how ya feed them. Fresh or brackish. So what I am really tryng to say is that I really don’t think there is a right or wrong answer when it comes to that question. After all, I’m not the turtle and niether are any of you. So how would we really know which way is better? Mine seem happy and helthy in freshwater and I have acclimated some of my wild caught terapins over to freshwater with no problem.