To create a fish breeding pond, you will need the following items:
- 5000 gold coins
- 200 stones.
- 5 seaweed
- 5 green weeds.
You can earn 5,000 coins by exploring mines, selling crops, or completing assignments for the NPC in the city. The other three are much easier to get: you can get stones from the city’s mines and seaweed from fishing for a certain amount of time throughout the game.
When you have all the resources you need, go to the carpenter’s shop. Talk to Robin and then you can order a Fish Pond. Choose a pond spot and Robin will start working on it the next morning.