Aim the symbol between their mouths and release in the tiny circle before the center. Despite knowing this, I still can't beat Shino. The actual fishing seems to be bugged on my end or just way too laggy. The color bar in the rod just isn't cooperating. Refuses to move when I get there, barely moves at all, or switches directions constantly. It's much worse when it's an octopus. I barely get her to half health before she wins.