The Grooved Razorfish (Aeoliscus strigatus) is a fascinating reef fish closely related to Pipefish and Seahorses. This species is commonly found in coral reefs across the Indo-Pacific region, including around Koh Tao, Thailand.
The Grooved Razorfish typically grows to about 10-12 cm long. It stands out with its long, slim body and vertical stripes, giving it a sleek and streamlined appearance. With a pointed snout and long fins, it resembles a small, sharp dagger. Its color ranges from pale gray to white with a narrow reddish-brown to dark brown stripe along its side. The first dorsal-fin spine is moderately long and unjointed.
Camouflage and Schooling
Grooved Razorfish are typically seen swimming head-down in large groups or pairs. They display intriguing schooling behavior, moving in synchrony to evade predators. This behavior is facilitated by their fin arrangement: pelvic, tail, and dorsal fins are positioned towards the back of their body. Their elongated, laterally compressed shape aids stability and reduces drag, allowing for efficient navigation through narrow reef spaces. The long, slender pectoral fins provide precise control, helping them maintain a vertical stance, while the dorsal and anal fins help fine-tune their position and balance while hovering.
Their streamlined shape and vertical position among sea urchins or coral spines offer effective camouflage, making them less visible to predators. By hovering among corals, Grooved Razorfish blend seamlessly with the reef structure, making it easier to capture planktonic prey drifting by. Their swim bladder helps regulate buoyancy, allowing them to maintain this vertical position with minimal energy expenditure.
Feeding Habits
Grooved Razorfish mostly feed on tiny plankton, which are small organisms drifting in the water. They also eat tiny invertebrates, like small shrimp or worms. To catch their food, these fish use a special feeding technique. While they hover in a vertical position, they open their mouths slightly and use their fins to create a flow of water. This flow helps bring the plankton and small invertebrates closer to their mouth. Once the tiny creatures are close enough, the Razorfish filters them out of the water and swallows them. This way of feeding helps them catch small, floating food while they stay in one place among the corals.
Predators
Grooved Razorfish face predation from a variety of reef-dwelling predators. Their primary threats include larger fish such as groupers and snappers, which are capable of preying on smaller fish. Additionally, moray eels and some species of octopus may pose a risk, as they are adept at hunting in crevices and among corals where the Razorfish might seek refuge.
Reproduction
The Grooved Razorfish’s reproduction involves some interesting behaviors. During mating, they form pairs or small groups where the male and female swim close together. The female releases eggs, which are fertilized by the male. After fertilization, the eggs are left in a safe spot within the reef, where they develop until hatching. The young fish, or larvae, are initially very small and transparent. They drift with the currents until they grow larger and start to resemble adult Grooved Razorfish, eventually moving to the reef where they will continue their growth and development.
Where to Find Grooved Razorfish on Koh Tao
On Koh Tao, Grooved Razorfish are often found in groups and tend to swim just above the seabed. They can occasionally be spotted at dive sites such as:
Chumphon Pinnacle,
Southwest Pinnacle,
Hin Wong Pinnacle,
and Sail Rock.
