Bluehead Wrasse in Cozumel
Bluehead Wrasse (Thalassoma bifasciatum) in Cozumel: how to identify it, where it is reliably seen, and what it is commonly confused with.
One fish, three completely different looks. Most of what you see are small yellow fish with a dark stripe; the blue-headed version that gives the species its name is the large terminal male, and there is usually only one per patch of reef.
Quick ID
| Scientific name | Thalassoma bifasciatum |
|---|---|
| Group | Colourful Reef Fish |
| Typical size | Up to 25 cm |
| Depth range | 1–40 m |
| When to see it | Year-round |
| Active | Day |
| Conservation status | Least Concern |
How To Identify It
Terminal males have a deep blue head, two black bars and a green-blue body. Initial-phase fish and juveniles are yellow with a dark lateral stripe or a row of dark blotches.
Where You Will See It In Cozumel
Everywhere, on every reef, at every depth a recreational diver goes. One of the most abundant fish on the island.
Reliable sites: Paradise Reef, Chankanaab, Yucab, Tormentos, Paso del Cedral.
Behaviour
Bluehead wrasse change sex. Fish begin as females or as initial-phase males; the largest becomes a terminal male, turns blue-headed and defends a spawning site. Remove that male and the next fish in line changes.
They also act as cleaners when young, picking parasites off larger fish — worth watching at a cleaning station.
Commonly Confused With
- Yellowhead wrasse — Yellow head, not blue, and a dark bar behind the pectoral fin.
- Juvenile parrotfish — Blunter head and a beak; the wrasse has a pointed snout and separate teeth.
Diving Etiquette And Safety
Keep fins off the reef and hands to yourself. Nothing here needs to be touched, moved or provoked to be seen well.
Part of the Cozumel marine life guide · see Cozumel dive sites · plan your Cozumel dive trip
Photo courtesy of the Cozumel Coral Reef Restoration Program, used with permission.
Bluehead Wrasse Photos