Massive migrating school of surgeonfish discovered in the Philippines

Two weeks ago, we were in the Philippines scouting for new and exciting corals to grow at the RVS 4-star Mariculture facility. While diving certain areas which have perhaps never been seen by humans using SCUBA equipment, we stumbled upon an incredible sight – a massive “school” of surgeonfish stretching as far as the eye can see.

We use the term “school” to describe this gathering of surgeonfish with quotes because this assemblage was well over a million individual fish! For at least the two hours that we were moored in this particular location near Lubang Island, this huge group of surgeonfish were coming from the West, and headed towards the east, in a living, moving ribbon that was at least several hundred meters wide.

Extraordinary claims require extraordinary evidence and not only do we have a multitude of pictures, we also have this incredible video of this huge swarm of surgeonfish, representing only two out of the 120 minutes that we personally witnessed. Take this small snapshot and multiply it by 60 and you can imagine how we estimated this huge population of surgeonfish to be in the neighborhood of millions of individuals.

Like the huge annual migrations of red crab at Christmas Island, this huge density of individual fish is not a sustainable phenomenon, which is why we believe that this gathering was some kind of migration for this species. Nearly all of the fish in this massive school were colored very dark, with the lightest hint of blue on the edge of their posterior fin margins and tail.

ctenochaetus cf striatus-1 — The huge swarm of surgeonfish above with the occasional stop for grazing – in this snapshot we captured this photo of Ctenochaetus cf. striatus.

However, about one in 50 to 100 individuals of this school clearly were the surgeonfish that is currently referred to as Ctenochaetus cf. striatus, with attractive blue and orange striping, and beautiful orange tips to its caudal fin. Therefore we belive this school was made up of the striated species of bristletooth surgeonfish, but without catching one and looking at it more closely, there’s no way to be 100% sure what kind of surgeonfish this was.

ctenochaetus cf striatus-2 — The attractive surgeonfish known as Ctenochaetus cf. striatus made up a small percentage of this huge school of migrating fish.

Unlike most recreational divers, when we are diving tropical marine locations, we could care less about megafauna and pelagic marine fish. If there’s corals to be seen, we keep our mask a few inches from the reef and rarely take a moment to look up and take in the whole reef scene.

That being said, seeing this huge migration of surgeonfish was an incredible surprise, and truly the experience of a lifetime. We still don’t know much about what was going on with this huge school of surgeonfish, where they were coming from, or where they were going; we’re just glad we got to see and documented the amazing spectacle to share with you.

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Jake Adams

Jake Adams has been an avid marine aquarist since the mid 90s and has worked in the retail side of the marine aquarium trade for more than ten years. He has a bachelor’s degree in Marine Science and has been the managing editor of ReefBuilders.com since 2008. Jake is interested in every facet of the marine aquarium hobby from the concepts to the technology, rare fish to exotic corals, and his interests are well documented through a very prolific career of speaking to reef clubs and marine aquarium events, and writing articles for aquarium publications across the globe. His primary interest is in corals which Jake pursues in the aquarium hobby as well as diving the coral reefs of the world.