Lawnmower Blenny

Salarias fasciatus

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The Lawnmower Blenny (Salarias fasciatus) is known under several different common names in English, including Algae Blenny, Jeweled Blenny, Jewelled Blenny, Banded Blenny, and Banded jewelled-blenny. The term blenny is sometimes substituted with rockskipper, e.g. Lawnmower rockskipper, Algae rockskipper, Jeweled rockskipper and so on.

The Lawnmower Blenny belongs to the family Blenniidae, the combtooth blennies.   

Salarias fasciatus has not been evaluated for the IUCN Red List of Threatened Species.

Geographical distribution, habitat and habits

The Lawnmower Blenny lives in tropical parts of the Indo-Pacific, from roughly 30° N to 15° S. Its geographical range includes the Red Sea and the eastern coast of Africa and stretches eastward to Samoa and north to the Japanese Ryukyu Islands. Southwards, the Lawnmower Blenny can be found down to Australia's Greet Barrier Reef and New Caledonia. 

The Lawnmower Blenny is primarily found on reef flats, seaward reefs, and in shallow lagoons. Estuarine environments where rubble patches of reef flats and slopes are covered in prolific algae growth are also appreciated by this species. The typical Lawnmower Blenny habitat consists of corals, rubble and/or sand. Lawnmower blennies stay fairly close to the surface where the sunlight is strong enough for rich algae growth and they are rarely encountered below 8 meters / 26 feet.  

Size and appearance

The largest scientifically measured Lawnmower Blenny was 14 cm / 5.5 in. Unlike some other blennies, the Lawnmower Blenny is not equipped with fangs or venom glands. 

The Lawnmower Blenny is a rather drab looking creature. Just like most other blennies, it has an elongated body and the dorsal fin extends the length of the body. The fish is whitish and decorated with tan or gray bars and streaks along the sides. The head is blunt and the face is adorned with small light-blue and black dots. The eyes are located high up on the head. Around the face of the fish you can see elegant projections similar to delicate feathers. These tufts are known as “cirri”.

Keeping Lawnmower Blenny in aquariums

The Lawnmower Blenny derives its name from its remarkable ability to keep algae growth in the check in the aquarium and this – combined with its charming disposition – has made it a popular aquarium inhabitant among marine aquarists despite its rather plain appearance. It is famous for eating hair algae; a type of algae shunned by most other algae eating fish species.  

It is important to keep the Lawnmower Blenny in a large enough aquarium; 35 gallons / 130 litres is considered a minimum. Wait until you have a well established aquarium with thriving algae before you purchase a Lawnmower Blenny. When kept in a large enough aquarium filled with natural algae growth, this species is really hard and easy to care for.

You can expect your Lawnmower Blenny to spend most of its time perched on rocks in the aquarium, when it is not grazing algae. The Lawnmower Blenny is considered reef safe, but it can nibble on stony corals and clam mantles. If kept in an aquarium that is too small or crowded, the Lawnmower Blenny can become aggressive and start chasing other fish.

Keeping more than one Lawnmower Blenny in the aquarium is usually not a good idea, unless it is a compatible pair. This species is known to vigorously attack even its own reflection in the glass. Keeping it with other blennies can also be tricky. If you have a cleverly decorated 55 gallon / 200 litre aquarium or larger you might however be able to house more than one specimen of the same or similar species since this will make it possible for them to stay away from each other.  

The aquarium set up should include caves and other suitable hiding places for the Lawnmower Blenny. The fish likes to burry itself in the substrate during the night with only its eyes protruding, so substrates with sharp edges that might injure the fish must be avoided.

The recommended water temperature when keeping Lawnmower Blenny is 24-29° C / 75-84° F since this species hail from tropical parts of the ocean.  

Feeding

The Lawnmower Blenny is chiefly vegetarian and will feed by using its teeth (it is a so called combtooth blenny) to scrape algae off rocks and other surfaces in the aquarium. They are famous for eating hair algae, but are even fonder of film algae. Some specimens never touch hair algae.

If there isn’t a lot of algae in your aquarium, or if you have only one type of algae, it can be a good idea to supplement the natural algae growth with other types of food to ensure a varied and nutritious diet. You can for instance give your fish dried or frozen food for herbivore and algaevore fish. Occasional servings of bloodworms and similar meaty foods are appreciated and beneficial, but should not be offered too frequently or in large quantities.

Never place a Lawnmower Blenny in an aquarium where there aren’t a lot of algae and expect it to survive on the food you give it only. The recommendation above to supplement with other food is for blennies that already display a healthy appetite in the aquarium but are so efficient eaters that the algae can’t grow fast enough for them.

It can be hard to get your Lawnmower Blenny to eat when it arrives to its new home. Keep the water quality supreme and make sure that all aspects of your aquarium are suitable for the blenny. Avoid purchasing specimens that do not graze algae in the fish store and pass up specimens with pinched flat stomachs. Heavy breathing and a mouth that gapes wide open is another sign of starvation.

If you are an experienced and dedicated fish keeper with a good portion of luck you might be able to nurse a starving Lawnmower Blenny back to health by placing it in a quarantine aquarium with plenty of natural algae growth and slowly encourage it to start eating again.

Breeding Lawnmower Blenny

Both sexes have two spines in the anal fin, but in females one or both of them may be smaller or even embedded. In the male fish, the spines may be capped with fleshy tissue.

The Lawnmower Blenny is an egg-laying species that produces adhesive eggs.

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