Glossary

Field mark

Answer in brief

A visible feature that reliably separates one species from a similar one.

In practice

Good field marks survive changes in color and lighting: jaw length, spine counts, spot placement, tail shape.

Where it comes up

The linked entry shows the term in use on a real identification problem, and how CatchVault handles that step.

Questions & answers

What is a field mark on a fish?

A visible feature that reliably separates one species from a similar one. Good field marks survive changes in color and lighting: jaw length, spine counts, spot placement, tail shape.

Sources for this entry

FishBase: Scientific database of fish species, names, ranges and morphology.

Practical guidance is original editorial writing. App details come from the developer’s published descriptions, checked 9 November 2026.

Continue this reading path

What a fish identifier app does Glossary CatchVault as a fish identifier

How the related websites connect

This reference is published alongside CatchVault. Species profiles live on the CatchVault website, and sister references cover fishing apps in general and fishing regulations.

Cite this entry

Best Fish Identifier App. “Field mark.” Content reviewed 9 November 2026.

https://bestfishidentifierapp.com/glossary/field-mark/