Cortez rainbow wrasse with Dive Zihua

Cortez rainbow wrasse with Dive Zihua

Hi fish lovers!

I want to introduce you to some of the marine life present on the Pacific coast of Mexico and mostly here in Zihuatanejo-Ixtapa. My first pick, is the Cortez Rainbow wrasse (Thalassoma lucasanum). I choose this specie of wrasse because summer is all about colours and that specie shows plenty. We see this specie of fish very often during our dives and they are particularly beautiful to look at.

3 steps to get to the rainbow

The Cortez rainbow wrasse passes through 3 phases before getting his final rainbow colours.

Juvenile phase

The first one is the juvenile phase. We have different dive sites with beautiful shallow reefs and this is where you can see them in abundance and by that I mean they are everywhere surrounding you. They are also very curious and sometimes like to clean you like they do other fishes from their parasites and debris. During their juvenile phase, the rainbow wrasse is about 4 cm (1 ½ in) long. They are stripped horizontally with prominent black lines and yellow and pink-red.

Initial phase

In the initial phase they are a little bit bigger and the coloration changes. The upper body is darker colour with a bright yellow line in the middle and a pinkish belly. In the initial phase, the wrasses are sexually mature and will reproduce in large aggregations near reef tops where they spawn in large groups by rushing near the surface in a tight ball just before releasing white puffs of gametes.

Terminal phase

The terminal phase shows a very different fish but still very colorful. The body is no longer stripped horizontally but insteads shows a beautiful blue or purple head with a yellow saddle patch behind the head. The rest of the body is purple-pink with a blue tail. They grow to approximately 13 cm (5 inch). You do not meet the Cortez rainbow wrasse at depth, they prefer to stay above 30m (98f) deep. Compare to the two previous phases the terminal phase is more of a solitary fish and will mate one on one with the female not in a group.

Scuba diving with the Cortez rainbow wrasse

Here in Zihuatanejo-Ixtapa, the rainbow wrasse is pretty common especially the juvenile and initial phase. They make our snorkelling experience very amusing because we get to be very close and they are such a pretty fish. When we dive on shallow reefs, they swim around the top of the reef by big groups.

While scuba diving the adult rainbow wrasse catches your attention very easily with their beautiful colours. They are pretty shy and won’t let you get to close but if you keep your distance, you will be amazed by this very active fish. They are fast swimmers and they enjoy moving from rocks to rocks looking for food like invertebrates, crustaceans, worms and small fish.

Of course there are plenty of fish in the see and I hope to be able to make you learn about them. I will try to show you a new specie every month. If you are curious about the fishes you can find here come scuba dive or snorkel with us and it will be my pleasure to tell you all I know about them.


Owner, Scuba Instructor and Marine biologist at Dive Zihua

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