Yeah, mahi-mahi, silver sharks, and hammerhead sharks are the most profitable fishes, but they're all ass to catch. Mahi-mahi is a level 50 one star fish in a low level area that can only be caught between 10am and 6pm in-game time. Both sharks are needed for the shark oil recipe but each have separate fishing locations. Sometimes they have to be mooched depending on where you're fishing.
Mahi-mahi used to be 8-10K per fish on Sargatanas. Now they're down to 1.5Kg because of all the undercutting.
XI Wiki


