I played the game for a bit and I think the mechanics are well-balanced. The game is fairly short in the demo. There are a few mechanics you can play with to try to optimize the money you get, those being the fish stock/amount of which fish you have in your pond, the ticket prices and the fish markup. The demo is locked to the first 10 fish, all 25 being available in the purchasable version. The upgrades are also locked to 4 for the fishing rod and 2 for the decoration upgrades.

The mechanic of closing the pond access yourself is useful for when you are too popular for the number of fish you have and don't want negative reviews.