The cats don't "pay" you with fish. They simply drop them on the way out.
Tubbs collects food, such as fish, so it's no wonder he leaves a lot behind if you let him eat. If you don't let him finish, he probably drops less since he's focused more on his stash than the meal he just ate. It was originally a minigame from a fighting game.
Because why else the cats have power levels?- The power levels are mainly a priority thing to show which cat will get to play with which toy.
Plot twist: You're playing as a cat as well.
- It was a world of cats, where the silver and gold fish are the main currency. Your 'backyard' is more like an 'amusement parks' of short, modeled after a human's house. The other cats are simply visitors.
- It also explained why some cats are anthropomorphic.
- Jossed, as evidenced by the description of the Large Cooling Mat ("Your hands leave deep prints in the squishy gel, but it should be okay for cats")
- There's the movie as well, in which the yard owner is clearly a human. True, it's not the game itself, but still.
Glunkus and Hobo will eventually be added to the game.
- Though they won't show up as the original creator of them described, they will be added later as a sort of shout out to the fandom. Bonus points if Glunkus only shows up during Halloween, and Hobo only if you run out of money and use the cheapest of items.
Minigames will eventually be added to the game.
- Little ways you can play with the cats in your yard for additional fish.
Eventually, there'll be cat named Salt, to go with Pepper.
- Additionally, there will eventually be a counterpart to Pickles named Onions.
Peaches is some sort of love god.
- Hence the heart on their fur coat.
There will be an update that shows Bengal Jack and Whiteshadow facing off against each other.
Tubbs will get a Super Mode in Neko Atsume 2.
Which allows them to eat from the indoor bowl too.