It's super refreshing to see a game mechanic like your taking pictures one, and the visuals are wonderful! Personally I prefer WASD style controls for something like this, as it can be conflicting when the mouse location has to serve 2 purposes: in this case (1) the direction the player moves to and (2) has to hover over the fish you want to photograph. WASD/arrow keys for movment here let the player have a bit more control in my opinion.
Would love to play again when the upgrade system is implemented!