No, Shanks has not been shown visiting Fishman Island in the one piece series. While some of the other Yonko like Big Mom and Kaido have had interactions with Fishman Island, Shanks hasn’t been depicted going there.
His adventures and storylines have taken him to many places, but Fishman Island hasn’t been one of the, so far. Shanks is more often seen interacting with characters in the New World and having significant encounters elsewhere in the One Piece world.
So, while he is one of the key figures in whole One Piece universe, Fishman Island remains a place he hasn’t visited yet.
