With a slayer weapon/spellbook, anything gm level works fine fishing. I have a gm mage fisherman that uses a slayer spellbook and kills deep sea serps with 2 e-bolts, and my archer fisherman that uses a slayer bow takes them out with 2-3 shots. Water els are super easy too. I suppose if you are tossing white fishing nets, myst would be good for the RC to be cast when you toss it in.