Yellowtail Damselfish in Cozumel
Yellowtail Damselfish (*Microspathodon chrysurus*) in Cozumel: how to identify it, where it is reliably seen, and what it is commonly confused with.
Adults are dark brown-blue with a bright yellow tail. Juveniles — often called jewelfish — are deep blue scattered with brilliant electric blue spots.
Quick ID
| Scientific name | Microspathodon chrysurus |
|---|---|
| Group | Colourful Reef Fish |
| Typical size | 12–20 cm |
| Depth range | 1–15 m |
| When to see it | Year-round |
| Active | Daytime |
| Conservation status | Least Concern |
| Notes | — |
Where You Will See It In Cozumel
Shallow coral and fire coral at Paradise Reef, Chankanaab and Playa Corona, each fish holding a small patch.
Reliable sites: Paradise Reef, Chankanaab Reef, Playa Corona.
Behaviour
Fiercely territorial farmers. They cultivate patches of algae, weed out the species they do not want, and charge fish many times their size — including divers who hover too long over the patch.
Commonly Confused With
- Other damselfish — The bright yellow tail on a dark body identifies the adult; the electric blue spots identify the juvenile.
- Blue chromis — Blue chromis are slender, bright blue and school in open water.
Diving Etiquette And Safety
Nothing required beyond amusement. A damselfish charging your mask is defending a patch of algae, not attacking.
Part of the Cozumel marine life guide · see Cozumel dive sites · plan your Cozumel dive trip
Photo: Paul Asman and Jill Lenoble, CC BY 2.0, via Wikimedia Commons.
