What I have noticed is as soon as you hit level 10 you are able to go fishing. No one really does this, but I have noticed a
very large amount of gold can come from this. It takes 50 gold to buy a fishing ticket and 180 gold for 36 harpoons. As you fish if you catch even one fish they usually will sell on the market anywhere from 2000-8000. Some of the really rare things that sell for anywhere from 100 thousand to 600 thousand Are Salmon eggs, Violent Tahtich, and Violent Tahtich Junior.
Also upon catching some fish you will find that they are treasure chest. In these chest a large number of items can appear. Most can be used for side quest and crafting for your expertise. These items can also sell on the market for large prices at
times as well. I personally went from 10 thousand to 3 million as soon in only 3 hours of fishing and had plenty of resources to use later when I obtained my expertise. I am not completely sure if this is affected by level and number of people fishing but at lower levels I noticed many more of the Tahtichs then I do now and on average I see one every 30 minutes. I also seem to find more when I am in groups with more people than by myself. I have found to keep myself from being bored while fishing is to go on the boat and fish with friends while we dual. It will give you no repair cost and maintains some hilarity to it if you are close in levels.