Fish of Koh Tao: Your Guide to What You’ll See While Diving with Chalok Reef Divers
Introduction
This is the third installment in our blog series exploring the vibrant and diverse marine life around Koh Tao. In this part, we’ll showcase even more fascinating creatures, from striking wrasses to the peculiar pufferfish. Each dive with Chalok Reef Divers is an opportunity to meet these underwater wonders up close! In case missed it click for Part 2 of our Koh Tao Fish guide.
Orangespine Unicornfish
About: The Orangespine Unicornfish is one of Koh Tao’s most vibrant residents, with a sleek body, bright orange markings, and sharp spines near its tail. These herbivorous fish are usually seen in small groups grazing on algae along the reefs.
How Common? Very common, particularly near healthy coral gardens.
Fun Fact: The Orangespine Unicornfish’s sharp tail spines are its primary defense mechanism—handle with care if you see one up close!
Commonly Found At Dive Sites:
- Aow Leuk (very common)
- Hin Ngam
- Hin Wong Bay
- Japanese Gardens (shallow coral zone)
Black Spotted Porcupinefish
About: The Black Spotted Porcupinefish is a charming oddball with its big eyes and habit of puffing up like a balloon when threatened. Their dotted patterns and boxy shape make them a favorite for divers and photographers alike.
How Common? Fairly common, often spotted hiding in coral crevices.
Fun Fact: When inflated, the porcupinefish’s spines stick out, making it a prickly meal for any predator.
Commonly Found At Dive Sites:
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Hin Wong Pinnacle (especially cavey north side)
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Laem Thian Caves
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Tanote Bay (along boulders and coral heads)
Sling-Jaw Wrasse
About: The Sling-Jaw Wrasse is known for its unique feeding mechanism: its jaw extends out like a slingshot to snatch prey. These colorful fish are often found darting between coral heads.
How Common? Occasionally seen but always an exciting find.
Fun Fact: The Sling-Jaw Wrasse can extend its jaw to nearly half its body length, making it one of the most unique feeders in the reef ecosystem.
Commonly Found At Dive Sites:
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Laem Thian Bay
-
Hin Ngam
Christmas Tree Worms
About: These colorful, spiral-shaped worms are tiny but pack a visual punch. Found burrowed into coral, they come in a rainbow of colors and retract into their tubes when disturbed.
How Common? Very common and easy to spot on coral formations.
Fun Fact: Despite their name, Christmas Tree Worms are filter feeders and play a vital role in maintaining the reef’s ecosystem.
Commonly Found At Dive Sites:
Tanote Bay
Red Lionfish
About: The Red Lionfish is a striking predator with its feathery fins and bold stripes. While beautiful, these fish are invasive in some regions but remain a natural part of Koh Tao’s ecosystem.
How Common? Fairly common, especially in deeper waters.
Fun Fact: Lionfish have venomous spines, so admire their beauty from a safe distance.
Commonly Found At Dive Sites:
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Green Rock (inside swim-throughs)
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Shark Island (deeper eastern edge)
Parrotfish
About: Parrotfish are the reef’s gardeners, known for their vibrant colors and habit of crunching on coral to feed. Their sand-like waste contributes to the beautiful white beaches of Koh Tao.
How Common? Very common and often seen during shallow dives.
Fun Fact: Some species of parrotfish sleep in a cocoon of mucus to protect themselves from predators.
Commonly Found At Dive Sites:
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Hin Ngam
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Tanote Bay
-
Mango Bay (southern reef)
Blackeye Thicklip Wrasse
About: The colorful Blackeye Thicklip wrasse is named for its prominent lips and striking black eye markings. They’re active swimmers, darting among coral heads in search of small invertebrates to eat.
How Common? Fairly common and frequently seen on reef dives.
Fun Fact: Wrasses play a role as “cleaners” on the reef, eating parasites off larger fish.
Commonly Found At Dive Sites:
-
Hin Ngam
Smooth Tailed Trevally
About: The Smooth Tailed Trevally is a streamlined predator often found hunting in small schools. Their silvery bodies glimmer in the sunlight as they move swiftly through the water.
How Common? Fairly common, especially near deeper drop-offs.
Fun Fact: Trevally use teamwork to herd smaller fish into tight groups, making them easier to catch.
Commonly Found At Dive Sites:
-
Hin Pee Wee
Conclusion
In this third part of our series, we’ve explored a mix of colorful, quirky, and captivating marine life. From the dazzling Orangespine Unicornfish to the functional beauty of Christmas Tree Worms, Koh Tao’s reefs never cease to amaze. Keep an eye out for the next installment, where even more underwater wonders await! View more in Part 4 of our Fish Guide to Koh Tao.