* From your grandpa: He will give you a basic fishing rod as part of the story progression. This happens fairly early on, after you've gotten a few things set up on your farm.
* From the shop: You can also buy fishing rods from the shop once you've unlocked it. The shop will have different types of rods available, some offering better fishing capabilities.
It's important to note: In TOT, fishing isn't a major gameplay mechanic. It's more of a side activity for earning a little extra money or finding rare items.