40-> 50

[Meister]

Don't bother leveling fisher. You can get Red Coral far more easily from the level 15 dunegon just outside Limsa, called Shposhae. Proceed to the area with a large glowing clam and wait for the Shadow Lurkers to spawn. Some seekers will make their way to it, don't kill them, they will cause the Shadow Lurkers to pop from the clam.
Easily get a stack in an hour or so with +1s as well.
Lots of coffer keys for additional loot.

Selling the resulting rings is a pain. I've had almost 50 of them at one point in my inventory and ended up npc'ing most of them. On my server they sell for 9k in wards, I found it much more useful to spiritbond them and sell the materia.

While making coral rings + bracelets is a good way to get to 45~ or so. Level 45, 50 leves will become available at 45 or maybe sooner. These will provide much larger exp yields, and some nice ingots as well.

[Melinia]

Don't bother leveling fisher. You can get Red Coral far more easily from the level 15 dunegon just outside Limsa, called Shposhae. Proceed to the area with a large glowing clam and wait for the Shadow Lurkers to spawn. Some seekers will make their way to it, don't kill them, they will cause the Shadow Lurkers to pop from the clam.
Easily get a stack in an hour or so with +1s as well.

You got better results than I did. After an hour or so down there I think I had around 2-3 dozen Red Coral, with a couple of +1s as well.

That's nothing to sniff at by any means (particularly since each one you get is another synth), but it's something to be aware of.