So one night Lavawhle and I were talking about a castnet to speed up fishing. The castnet will an given out by fisherman mugan after you catch 10 sunfish, 10 catfish and 8 bass (very easy) after you do that you get a castnet.
Using The Castnet- This can be used at every fishing spot in the game. The first thing you do is equip it to your side (like the rod) next you grab it from both sides and throw it at the little bubbles you see in the water next you pull the rope in and the pulling works the same like the white to red on the rod and you get 10 to 25 of random fish that spawn in the area. it takes 10 to 15 minutes use again. Also you get a chance of 3 to 4 legendary fish that are spawning in the area. plus it does work with fishing pots.