What is Fishermen (Polkadot)?

Fishermen is a technical term used within the Polkadot blockchain protocol to refer to full nodes that are responsible for maintaining the integrity of the network and nodes. The job of fishermen is to monitor the Relay Chain and other parts of the protocol to pinpoint and report unwanted behavior to validator nodes. Rather than packaging state transitions and producing the next parachain blocks like Polkadot collators, fishermen monitor the process to make sure that no invalid state transactions are included. Fishermen typically stake a small amount of DOT initially, and are rewarded upon identifying unwanted behavior on the network.