Fisher is the easiest class in the game to cap out. Sit at a Grade 7 or 10 node and you can pretty much cap out within a month and a half fishing a few hours a day. Less if you're masochist and/or have sweat of brow. It's much different from mining and botanist, although there are ways to speed those up also. They just can't be powerleveled to that extent since there are no higher grades than 5 for them.