It's not bad, and it does show the dev put a lot of effort into this, but there's a reason why fishing games tend to be minigames inside other larger games. The gameplay is fun for a while but eventually it gets too repetitive, even if you add a lot of other elements like potions, upgrades and all that, they don't significantly change the gameplay, it's still the same minigame with some tweaks. This might work inside another game though (avoiding the copyright infringement of course).