A more thorough explanation:

Definition: Common of Piscary is a legal right that allows someone to fish in waters on another person's land.

Example: If a person owns a lake on their property, but they allow their neighbor to fish in it, then the neighbor has the common of piscary.

This means that the neighbor has the right to fish in the lake, even though they don't own it. This is a legal right that has been granted to them.