In this world you can farm for coins it is in hardmode and not in expert. The farm is at the right sea you will need a slime staff forged to broken and tiki-armor and pygmy necklace and a lucky coin. You will need to stand in the middle of the water to start making it work. DO NOT USE BANNERS!!! If you use banners it will make you do more damage to the piranhas and the other mods which is what you don't want. You dont want to do more damage because you want more moneys.
