Right now I think fishing is pretty boring. You just cast your line in and then wait for a bite, left click, repeat. What I think would be good is if there was a fishing minigame where you have to keep a box on the fish, or have a ring close in on a tiny circle and you have to time it right when the ring touches the circle, or maybe have an 'interest meter' for the fish which fills as you keep it on it, but if you let it get too high then it eats the bait and goes away. And then add a reeling button that takes time and lowers the interest, and if the interest bottoms out before you reel it fully in then the fish escapes. Then you could make it so better fish have a smaller bar and faster bottoming out, so that there is some finesse and timing required.