Worlds/Graal Bomy Lands/Fishing
Fishing Rod
The 
Fishing Rod, if you have bait, will allow you to cast your line into water and pull it in -- hopefully with a fish on the line. Press D to cast, then press A to reel the line in.
You can purchase the Fishing Rod from the Harmonia fishing shop for 20g.
You can find out how many pounds of fish you currently have by saying show fishes.
Baits
Baits allow you to catch fish, the better your bait, the heavier the fish you can catch. A bait will never run out from use.
You can purchase baits from the Harmonia fishing shop for various prices.
Bait 1 (10g)
Can catch fish up to 3 pounds.
Bait 2 (30g)
Can catch fish up to 8 pounds.
Bait 3 (100g)
Can catch fish up to 12 pounds.
Locations
You can fish anywhere there are fish, although many fishermen prefer to fish in spots where many fish are present and tend to not move that much.
Underground Lake
The Underground Lake fish pond can be found close to the Underground Lake train station. There is also a fishing shop nearby where you can sell your fish. This fish pond is a popular spot for fishing.
The fish in this pond weigh up to 3 pounds each.
Silverstun Pier
Silverstun's Sea can be found in the north-east region of Graal Bomy Lands. You can rent a boat here to help you get to more fish (Not functional right now!!).
The fish in Silverstun's Sea weigh up to 12 pounds each.
Selling your catch
You may sell your fish at the Harmonia fishing shop or the Underground Lake fishing shop, which both buy 15 pounds of fish for 1g.