A Good Rod is an item that can be used to fish Pokémon that are found in water. It has a 1 chance of being dropped by a Fisherman when defeated and can also be rarely obtained when using Forage on water with a Water-type Pokémon. It is possible to catch rarer Pokémon with a Good Rod than a Old Rod, but the rarest of catches are only accessible with a Super Rod. The possible catches depend on the biome that the player is currently in.
Goldeen and Magikarp can be caught regardless of the biome the player is in.