The Orange Spine Unicornfish (Naso lituratus), also known as the Naso Tang, is easily recognized by its striking black ‘Zorro’ mask with a yellow border that covers its eyes and mouth, along with bright orange lips and distinctive orange spines near its tail. It sports a single dorsal fin with a broad black band and can grow up to 45 cm. Adult males have a crescent-shaped caudal fin with a long filament at the tip, while juveniles are clad in a gray-brown hue with black, yellow, and white patterns. While famous for its bright orange spines, this fish doesn't have the "unicorn" horn-like projection found in some other members of the Acanthuridae family.
Special Defense with Built-In Blades
The Orange Spine Unicornfish packs some serious defense with its sharp, forward-pointing blades near its tail: sharp, forward-pointing blades called "caudal peduncle spines." These spines are found on both sides of the fish's tail base and are used primarily for defense. When threatened by predators or other fish, the Unicornfish can flick these spines towards the aggressor, making a potentially painful and deterrent "kick" to discourage attacks. The spines are not only sharp but are also equipped with a hard, bony structure, making them perfect for dishing out some pain if needed!
Behavior and Diet
The Orange Spine Unicornfish in Koh Tao are often spotted hanging out in pairs or small groups around shallow reefs. These fish are quite social and have a bit of a hierarchy but aren't overly territorial. They can get a little aggressive towards other species and sometimes even their own kind.
These fish feed on plankton and love brown algae. They’re busy throughout the day, primarily grazing on algae and occasionally snacking on coral polyps. Their specialized teeth are perfect for scraping algae off rocks and coral, which helps control algae growth and keeps the reef healthy.
Reproduction
In the world of Orange Spine Unicornfish, dominant males typically have a harem of multiple females. These males claim and protect their territory to attract females for spawning. When it’s time to spawn, they gather in schools, where the males compete for the females attention. Spawning happens in open water, with females releasing their eggs and males releasing sperm at the same time to ensure fertilization. After spawning, the fish return to their own areas in the reef.
Predators
Their main threats include larger fish like groupers and snappers. They are also vulnerable to sharks. Despite their sharp spines, these fish rely on their agility and schooling behavior to avoid becoming a meal for these predators. Humans can also be predators of the Orange Spine Unicornfish too, they mainly pose threats through activities like fishing for the aquarium trade or local consumption. Additionally, habitat destruction from coastal development, pollution, and unsustainable fishing practices can harm their populations by damaging their coral reef habitats and disrupting their food sources.
Where to find The Orange Spine Unicornfish on Koh Tao
The most popular dive sites around Koh Tao for spotting the Orange Spine Unicornfish are shallow spots like:
