Lawnmower Blenny

The Lawnmower Blenny (Salarias fasciatus) is a member of the combtooth blenny family Blenniidae, distributed across the tropical Indo-Pacific from the Red Sea and East Africa to the western Pacific. It is named for its habit of grazing algae from rock, rubble, and coral surfaces using specialized comb-like teeth. This species is common on shallow reef flats and lagoons and plays a notable ecological role in controlling algal growth on reef substrate. It is not considered at risk and remains widespread throughout its Indo-Pacific range, typically observed perched on rock or coral rubble rather than swimming freely in open water.

The Lawnmower Blenny is identified by:

• Stocky, elongate body reaching 10-14 cm with a blunt, rounded head
• Mottled brown, tan, and cream coloration with irregular dark blotches and fine spotting, providing camouflage against rock and rubble
• Small fleshy cirri (tentacle-like projections) above each eye
• A single long, low dorsal fin running most of the body length
• Comb-like rows of fine teeth adapted for scraping algae

Its blotchy, camouflaged coloring combined with a habit of resting propped on its pectoral fins atop rock or rubble helps distinguish it from more free-swimming reef fish of similar size.

Lawnmower Blennies occur across the tropical Indo-Pacific, from the Red Sea and East Africa to the Philippines, Indonesia, and the western Pacific. They inhabit shallow reef flats, lagoons, and rubble zones at depths of 1 to 20 meters, favoring areas with algae-covered rock, dead coral, and rubble substrate. They are typically found perched on the bottom rather than swimming in open water, using their pectoral fins to prop themselves on rocky surfaces. The species prefers warm, shallow tropical water generally between 24-29°C and is closely tied to algae-rich substrate for both shelter and food.

Lawnmower Blennies are solitary and territorial, each individual defending a small patch of algae-covered substrate against other blennies. They spend most of their time perched motionless on rock or rubble, using camouflage to avoid predators, and dart short distances when foraging or threatened. Feeding consists of scraping filamentous algae from hard surfaces using their comb-like teeth, a grazing behavior that helps limit algal overgrowth on reef substrate. They can rapidly change their coloration and pattern intensity to match their surroundings. Reproduction involves males guarding eggs laid in a sheltered crevice or empty shell until they hatch.