What is marking?

Marking is the technique of modifying a fish, such as removing a fin or painting its body, that helps identify it in some way. A common form of marking is the removal of the adipose fin to identify hatchery-reared fish. This method of marking helps anglers avoid retaining native fish species.

What is tagging?

Tagging is the process of adding some kind of artificial device or tag to a fish's body, rather than modifying the fish itself (such as marking, see above). Often these tags can be electronic devices that are passive (PIT, or passive identification tag) and require an external scanner to read them, or are active and have their own power supplies. Other forms of tags are simple ribbons or other forms of identification that are attached to the fish's body.