Cortez Damselfish: The Reef's Little Guardian

Small, bold, and endlessly busy, the Cortez damselfish is the kind of fish that notices you before you notice it. Its young are some of the most dazzling little fish on the reef. Here's how to spot it near Jacó, plus five fun facts.

Cortez Damselfish · Stegastes rectifraenum

How to spot the cortez damselfish near Jacó

Look low among rocks and rubble, where Cortez damselfish hold tiny territories. Adults are a dusky brown-gray; juveniles are deep blue above with glowing electric-blue lines and spots. You'll often spot one darting out to shoo away a bigger fish.

5 fun facts about the cortez damselfish

• Electric-blue youngsters. Juveniles are patterned with brilliant neon-blue markings that fade to plain gray-brown as they mature.
• Tiny but territorial. Each fish defends a small patch of reef, chasing off intruders far larger than itself.
• An algae gardener. Like other damselfish, it farms and grazes a patch of algae, which it guards fiercely.
• Eggs on the doorstep. Males guard nests of eggs laid right on the rock within their territory, fanning them to keep them clean.
• Born in the Eastern Pacific. It's native only to this coast, especially common from the Gulf of California southward.

The cortez damselfish is just one of many characters down there. See the whole cast in our Snorkel Jaco fish directory, or read real guest photos and reviews on the Snorkel Jaco reviews.