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Lawnmower Blenny

By | Last Updated: 18th May 2020

Lawnmower blenny, a notable marine aquarium species, gets its name because of its trait of consuming or mowing down algae growing at the bottom of the rocks or glasses in the aquarium. Its mottled pattern, bulging eyes, and slender body make it an immensely attractive aquarium fish, besides being popular among those keen to control their tank’s algae growth.

Lawnmower Blenny

Quick Information

Scientific NameSalarias fasciatus
Other NamesJewelled blenny, jeweled rockskipper, rock blenny, algae blenny
OriginIndo-Pacific belt stretching from the Red Sea and East African region to the Samoan and Micronesian Islands 
TypeSaltwater fish
Conservation StatusLeast Concern (by the IUCN)
Behavioral CharacteristicsCalm, peaceful, and curious about its environment, but could get aggressive with other lawnmower blennies  (of the same sex) or similar-looking species
School SizeMostly kept singly, in pairs, or small schools of 3 – 4 fishes
Physical TraitsElongated, slender body like snakes or eels; small head with whisker-like projections on it; smooth lip margins; large bulging eyes; a single dorsal fin, and a big mouth  
ScalesUsually absent, but might be present in some
ColorsOlive or brown body with dark-colored bars  and elongated or round white spots of various sizes
Size (How big do they get)Small; 5 inches (13 cm)
Lifespan (How long do they live)2 – 4 years
Sexual DimorphismPresent, but difficult to identify: Males are bigger with larger anal fins than their female counterparts
Probable Diseases White spot disease, ich, bloating (especially when overfed)
Approximate Price$25 – 40
Lawnmower Blenny Size

Tank Setup & Care Sheet Details

Care LevelBeginner
Tank Size30 gallons (113.5 liters) for single fish; 50 gallons (189 liters) for pairs; a bigger tank for keeping more individuals

Water Parameters

pH Level8.0-8.4
Temperature72 – 78°F (22.2 – 25.5°C)
Hardness8 – 12 dGH
Salinity1.020 – 1.025
Aquarium  Water FlowModerate to high

Tank Ambience

LightingModerate (cannot withstand bright lights)
Substrate TypeLive rock and sand
Tank MatesCompatible with: Other lawnmower blennies if dwelling together as a mated pair,  pistol shrimp, scooter blenny, and species that are less aggressive and not of a similar color or pattern as theirs

Incompatible with: Same-sex lawnmower blennies (aggression, mainly seen in males), starry blenny  and tailspot blenny(since both are  prominent algae eaters) diamond goby, dartfish,  pipefish, and seahorses
Suitable Position in the TankMiddle


Diet (What do they eat)Algae (filamentous microalgae, green hair algae, foraminiferans); spirulina; seaweed; fish eggs; small snails; corals as well as other invertebrates; chopped vegetables like spinach and lettuce may also be given
Frequency 2 – 3 times a day
Lawnmower Blenny Picture
Lawnmower Blenny Fish

Important Things to Know for Fish Keepers

  • Despite their small size, this fish needs big tanks to promote sufficient algae growth and also to have enough space for swimming.  
  • In case there is an insufficient amount of algae growth in your tank, opt for algae wafers or pellets as an alternate source. You can even place nori in between the live rock as a substitute.
  • Some owners have noticed heavy breathing and panting in their lawnmower blenny, which is often considered normal if the fish is healthy and eating well.  A combination of other signs like restlessness and low appetite would call for a fish veterinarian’s consultation. 


Q. Is the lawnmower blenny reef-safe?

The lawnmower blenny can be kept in a reef, but under supervision, as it may nip at shrimps, corals or other invertebrates.

Q.  Why is the lawnmower blenny called the rockskipper?

The lawnmower blenny is called the rockskipper since it would hop from one substrate to get its food.

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