Can you describe it in more specific way? If it was not in tournament (as you said it was not), are you talking about the size of fish caught? If so, what fish, and what was the size? Can you give us any specific example?
Just as a reminder: the game team is still making fine adjustments to the game, including fish size, so... during one of those adjustments, it is quite possible that some players may catch unusually larger size fish for that species. That does not mean these players had used illicit means to get these fish. It simply means these players were lucky to be catching these fish at the right time when the game team was making the adjustment.