Let's see, what can I say about fishing as a gathering job? How about it's really easy. It is not as slow as you might think. You get great experience points from it which of course, translate into point to be allocated. At this time I'm level 10 on pugilist and lancer but I'm level 14 experience point wise and that is a result of fishing.
It is extremely easy and if you decide to start this gathering job here are a couple suggestions I have from my experience. Find a grade 1 spot to fish from. If you are in Gridania start with lugworms and plan to catch crayfish.
The first few cast you may not be successful but do not give up as you will catch some crayfish here and there and after just a few your success rate will increase dramatically. When you cast make sure you change your depth setting each time. This will increase the variable and make your percentage of nibbles or bites increase. You will need to hit wait after setting the depth. After this you will get a message there is nothing biting or you get a nibble or you get a bite. If you get the nibble message I would hit wait. When you do this the next message you get will be you get a bite.
At this point you jig. You will get this cute little thingie that goes back and forth. What I normally do is let the dot swing almost to the end of the left side and stop it there. At that point you will get a message, most of the time, that you have a fish but cannot reel it in. At that point you jig again and let the dot move just a bit, approximately half the space to the center point of the gauge. At this point you will reel the fish in or you will get the messages "fish is taking line", "fish is tired", "you take in line". If you get fish is taking line: you need to go the opposite direction with your dot on the gauge. If you get the fish is tired: You need to just barely move the dot on the gauge a little to the right. In most cases, I normally try to make sure it lands just a little on top of the spot it stopped on previously. If you get the message you have taken in line you need to move a little more in the same direction as your last movement of the gauge. This can get a little tricky because if you move too much you will lose your fish. If you don't move it enough you'll get the taking in line message again or the tired fish message. At this point you normally have one more jig to get it right and if you don't you lose your fish.
I think as you try this out and find out just how easy it is you'll like this gathering aspect pretty well. I have not caught fish with the lugworms, just crayfish but the leveling and exp on crayfish was great all the way to level 5 and it really only took about an hour to get to that level for me. You can also use moth pupa to catch fish and you will catch occasional crayfish also.
This is just a few thought and things I have learned about fishing. It's not the gospel on it by any means but I'm hoping for those that want to give it a shot it'll help possibly just a bit in getting you started. If you have questions please feel free to check me in-game or here on the forums.
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