Kiki’s Vacation will be incomplete without fishing. It’s a fun mini-game that lets you catch rare fish and other aquatic creatures.
You will obtain the fishing rod from the “Daily Reward” on day three. Play the game on the third day to claim this reward.

Once you obtain the rod, it will be kept beside the radio in the shack. Tap on it and Kiki will start fishing.

To help her catch fish, tap on her when an exclamation mark appears above her. Wait for the big circle to appear above her. Tap on the circle when the thin outer circle converges with the thicker white circle.
The thick outline circle will turn green when the thin circle merges with it. Tap on it when it turns green. The cat will pull the rod harder until she pulls out fish from the sea. However, there’s no guarantee that you will catch fish when the white circle turns green.
Out of several attempts, I was successful only twice despite the fact that both circles converged quite a few times. I got sardines and shrimps. It may take several retries to successfully cast a line. You might be interested in watching the above video tutorial on how to catch fish in this game.
The game’s still pretty new, so I am not sure what would be the use of fishes. I am guessing some of the island dwellers might need them or she just loves fish (Of course!). Maybe they can be exchanged for shells from someone? Let me know about their uses in the comment section below.
Well I found out Boaris sometimes may take one of your fish to make you food for free and then asks you a question. He took from me shrimps and a squid, idk if they have other uses but that’s one of them.
You can get Boaris to cook some of the fish you have caught. That’s the only use of the fish I’ve seen so far.
You can actually fish anytime you want, the fishing rod is beside the radio so you just need to tap it and Kiki will fish.