Dark Cloud

This is available as soon as you have the oasis in Muska Lacka. You're going to go fishing here at dusk with a potato cake. The key here is patience. You're looking for ginormous fish. There are big fish here (Dens), but they're not the ones you're after. You truly want ginormous only - fish that you see and think "Whoa! There's a baby whale in the pond!" At the fishing sign, choose to fish then look at the fish as they break from the middle of the pond. If none of them is huge, quit fishing and try again; you don't have to move until you see that huge fish. It can get tedious re-setting, but don't go after random large fish, or you'll waste your high-priced potato cakes. Go after just the giants.

Barons average 700-800 fishing points each, so they're a great way to farm gems.

You can buy potato cakes from Brooke in Muska Lacka for 450 gold or steal them from diggers in the Moon Sea - the annoying mole things - on the fifth floor.