Razor Fish
Scientific name Aeoliscus strigatus
Razor Fish — often called Shrimpfish — are some of the most unusual fish on the reef. With extremely thin, blade-like bodies and a long tubular snout, they look almost two-dimensional from the side.
Their most distinctive behaviour is swimming head-down in a vertical position. This unusual posture helps them blend in with sea urchin spines, soft corals or branching reef structures. When startled, they pivot instantly and dart away while still maintaining their vertical orientation.
Around Koh Tao, they are usually found in small synchronized groups hovering near sea urchins, under ledges or along sheltered reef slopes between 5–20 metres. Their silver bodies often have a dark lateral stripe that enhances their camouflage.
Despite their delicate appearance, they are well adapted to reef life and rely heavily on group coordination for protection.
Find Razor Fish at...
Divemaster's tip
Look closely around long-spined sea urchins — Razor Fish often hover just beside or above them for protection.
Move slowly and avoid sudden fin kicks; the whole group will pivot and disappear in perfect synchrony if startled.
What do they eat?
Razor Fish feed primarily on small planktonic crustaceans and tiny invertebrates drifting in the water column.
Their long tubular mouths allow them to pick prey precisely while maintaining their distinctive vertical posture.
