I see no reason to pretend to be a fish in most part of the situations. It may only work sometimes in very specific spots against opponents that doesn't know you and your true play style.
If you are a good player, you are way more unpredictable than the weaker players, because you can adapt yourself to each game and situation to try to find some exploit to use against each opponent.
Strong players can have a balanced range of
bluffing and a balanced range of value betting. They can be aggressive and they will extract way more chips from you when they have their best
hands and when they are completely lost in the board, since they can polarize their range and turn your condensed/medium range of hands into
bluff catchers in very hard spots to do a hero call (obviously, they need to not bluff too much or too less; that's why I said they need to have a balanced range, otherwise, he would still be too much exploitable for even stronger players that would notice an unbalanced range more easily).