this is a very cute game! i really enjoyed the pace of the progression and it has probably one of my favourite fishing minigames of all time.
if you decide to work on it more, i think some qol improvements would be a "sell all" button for the fish and "upgrade max" button for the store (that just bought the most of both upgrades that you could afford). this would also help if you ever want to make the game longer.
it also would be nice to have music outside of the minigames, but this is a very minor preference.
overall, it's a very polished, wholesome, fun game!