Bait

Bait refers any item that can be used for Fishing. If you do not have any bait, you can use the Fishing Pole, but you will be unable to catch fish. Most critters that are insects or mollusks work as bait. If Truffle Worms are used as bait in the ocean it will summon Duke Fishron.

A piece of bait will only be used when a fish is caught. If you catch random junk, you will not loose any bait in the process.