[KoukiRyu]

Umm, with my experience so far...mind I don't have fishing very far, it's similar to skilling up a normal craft. For example, you want something that is above your skill level, but not drastically. The difference with fishing is that you can only line break, or catch the fish, and with crafting, your chance of making something much higher is extremely low, and skill up is low. So simply, for more skill ups, do something that is anywhere from 3-9 levels higher than you are for best results. This is just from my experience, and no hard facts or evidence.