Here's the breakdown:
* Old Rod: You can catch Corphish with the Old Rod, but it's not the most efficient method. The Old Rod has a limited selection of Pokémon, and Corphish is a relatively rare catch.
* Good Rod: The Good Rod is your best bet! It unlocks more water Pokémon, including Corphish, making it more likely to appear.
Tips for Catching Corphish:
* Location: Head to the water in Slateport City or the nearby areas.
* Bait: Use the right bait to increase your chances of finding Corphish. You can find this information in your Pokédex.
* Patience: It may take some time to find Corphish, so don't give up!
Good luck catching that Corphish!