Yellowtail Damselfish

Adult male yellowtail damselfish, photo taken by Dr. Alex Mustard. Please check out his website for more

Yellowtail Damselfish
Domain: Eukarya
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Family: Pomacentridae
Order: Perciformes
Genus: Microspathodon
Species: Chrysurus

I realized that I have yet to talk about fish, and because there are so many of them, I decided that it’s high time to start. I’m not sure why I wanted to kick it off with the Yellowtail Damselfish. I was going through a fish ID book I own, and it was the first one to catch my attention, maybe because I was already familiar with it. They are pretty neat looking fish and I want to share some interesting facts about them!

There are a lot of fish that are born looking completely different than their adult selves. Seriously, some fish can go through some intense changes before they settle into themselves as adults, but even then it might not be completely decided—I’m looking at you, clown fish! Yellowtail Damselfish are one of those species that look almost like a completely different fish at every stage of their life.

When they’re juveniles, they have these dark blue, almost black bodies that are littered in bright blue dots, with clear tail. Then in their intermediate stage, like high-school for humans, their dots shrink and their tail becomes a bright yellow. As adults, they lose the blue dots, but keep the dark color with the bright yellow tail.

Intermediate phase of the yellowtail damselfish, taken by Dr. Alex Mustard. Please visit his website, for more!

Yellowtail Damsel can be found in the warm waters of Florida, the Bahamas, and the Caribbean. They live on the tops of coral reefs where they eat algae and the polyps of fire coral. The juveniles tend to stick close to the branches of the fire coral where they hide from predators and loud divers.

The Yellowtail Damselfish was one of the species I had to learn how to identify for a course I took in college. Its tail is a pretty clear giveaway for the species, at least from the list I had to identify. It was especially easy for me to recognize the juvenile stage. However, the individual I had to identify was completely yellow with flecks of blue, which is a temporary change they can accomplish. Anyways, I found the younger stages to be beautiful and a joy to spot on the reefs!

Reef Fish Identification: Florida, Caribbean, Bahamas 2nd edition by Paul Humann and Ned Deloach

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