Really interesting mechanic, super original idea. I like the simple music too, it fits the game really well. The graphics commuicated to me well what I needed to do, even without a tutorial which is great design.
I found the game quite difficult - the fish movement is a bit too random. It'd be great if the fish had an anticipation frame ie a clue that it was just about to change direction. The controls were sometimes not that responsive - sometimes I would click once, but the hook would change direction once.
I'd love to see a bigger fish game with this mechanic with easier and more fish to catch - it would make for a nice chill game :)