The fishing theme is a good choice for this style of game. The letters at the end of a number to signify different amounts of money is a unique feature, and it's easy to understand, although it requires explanation to make sense.
Having the different items be more expensive as you purchase them more is also a feature that makes the game play experience feel more robust, since you never get to a point where you gain more money than you can ever possibly spend.
The music is also very chill, and while there are potential better choices for a fishing game, I'd say the music serves well to set the pace and atmosphere of the game.
Overall, good as far as clicker games go.