Lawnmower Blenny

Lawnmower Blenny Care and Breeding

The Lawnmower Blenny (Salarias fasciatus) is a popular choice for saltwater aquarium enthusiasts, thanks to its unique appearance, entertaining personality, and incredible algae-eating capabilities. This comprehensive guide will cover everything you need to know about keeping these fascinating fish in your aquarium, from their natural habitat and appearance to their care requirements and tank mates.


The Lawnmower Blenny is a captivating addition to any saltwater aquarium due to its quirky character and diligent algae-grazing habits. They are native to the Indian Ocean, the Red Sea, the Great Barrier Reef, and the waters surrounding Samoa and Micronesia. Known for their ability to blend in with their surroundings and change colors depending on their mood, these fish are both eye-catching and practical additions to your tank.

Species Profile

Scientific name: Salarias fasciatus

Common names: Lawnmower Blenny, Algae Blenny, Jeweled Blenny, Sailfin Blenny

Family: Blenniidae

Origin: Indian Ocean, Red Sea, Great Barrier Reef, Samoa, and Micronesia

Habitat: Shallow reefs, lagoons, and rocky shorelines

Size: 4 to 6 inches

Lifespan: 2 to 5 years

Temperament: Generally peaceful, but may show aggression towards other algae-eating fish

Diet: Herbivore, primarily consuming algae and biofilm

Minimum tank size: 55 gallons


The Lawnmower Blenny has a distinctive appearance that sets it apart from other marine fish. Its muted colors range from tan, green, or gray, with darker stripes or bands crossing their bodies. This banded appearance, known as cryptic coloration, helps them blend into their environment and avoid predators.

One of the most striking features of the Lawnmower Blenny is its large, pronounced head, which sports a prominent brow and blue or black dots across its face. Its eyes are encircled by bluish dots and feature a white stripe. These eyes can move independently of one another, allowing the Blenny to keep an eye on its surroundings at all times.

The Lawnmower Blenny’s body is covered with banded or beaded patterns, earning them the nickname “Jeweled Blennies.” Their wide mouths contain comb-like teeth that are perfect for scraping surfaces and capturing algae. Lawnmowers also have fan-like fins that help them navigate rocky terrain and elongated dorsal fins running the length of their bodies, giving them the “Sailfin Blenny” moniker.


The Lawnmower Blenny has an average lifespan of 2 to 5 years. They are considered hardy fish that usually fare well in aquariums, but monitoring their dietary intake and overall health is essential to ensure they live a long and healthy life.


Lawnmower Blennies typically grow to an average size of 5 inches, with adults ranging from 4 to 6 inches. The size they reach is influenced by their nutrition and overall well-being.


In the wild, Lawnmower Blennies inhabit shallow reefs, lagoons, and rocky shorelines at depths of up to 260 feet. They prefer environments free of other fish, allowing them to explore their surroundings and graze on algae in peace. These fish are generally docile, but they may nip at other fish if they feel threatened or sense competition for food.

Lawnmower Blenny Care

Caring for a Lawnmower Blenny involves providing them with a suitable tank setup, maintaining proper water parameters, and ensuring they receive a balanced diet. Here are some essential care guidelines for keeping a Lawnmower Blenny in your saltwater aquarium:

Tank Size

A minimum tank size of 55 gallons is recommended for a single Lawnmower Blenny to ensure they have ample space to graze on algae and explore their surroundings. If you plan on keeping a pair of Lawnmower Blennies, a tank of 100 gallons or larger is necessary.

Water Parameters

Maintaining appropriate water parameters is crucial for the health and well-being of your Lawnmower Blenny. The ideal water parameters for these fish are:

  • Water temperature: 72 to 78°F
  • pH levels: 8.1 to 8.4
  • Water hardness: 8 to 12 dKH
  • Specific gravity: 1.020 to 1.025 sg

Tank Environment

A well-established tank with plenty of live rock and algae sources is vital for a Lawnmower Blenny. They are bottom-dwellers who prefer to graze for algae on rocks and other surfaces. It is recommended to introduce Lawnmower Blennies to tanks that are at least one year old, as this ensures a more mature and stable environment.

The tank should include a sand or coral sand substrate, as this will minimize the risk of injury to your bottom-dwelling fish. Live plants are also a great addition, as they provide additional surfaces for algae growth and contribute to a more natural environment.


Lawnmower Blennies are herbivores, primarily consuming filamentous green microalgae, diatoms, and filamentous blue-green microalgae. They also occasionally eat invertebrates, fish eggs, sponges, tiny snails, and organic material that settles at the bottom of the tank.

One of the main challenges of raising these fish is ensuring they receive enough food. Continual observation is necessary to make sure they are grazing on surfaces and maintaining a healthy, rounded belly. In addition to providing a suitable environment for algae growth, supplementing their diet with prepared foods designed for herbivores, such as algae pellets or nori, is essential.

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Health and Disease

Lawnmower Blennies are susceptible to common fish diseases, such as Marine Ich, a parasitic infection caused by the organism Cryptocaryon irritans. This disease typically arises in tanks with poor water conditions and manifests as white spots on the fish’s body, fatigue, lethargy, and loss of appetite. If you notice signs of Marine Ich, isolate your Blenny and begin treatment with an over-the-counter anti-parasitic medication while also addressing any water quality issues.

Behavior & Temperament

Lawnmower Blennies are known for their curious and playful personalities, making them a delightful addition to any aquarium. They spend much of their day grazing on algae and exploring their surroundings, occasionally hiding or remaining stationary when they feel the need to rest.

While generally peaceful, Lawnmower Blennies may display aggression towards other algae-eating fish if they perceive competition for food. They may also nip at coral polyps if they are stressed or hungry, so it’s important to monitor their behavior and adjust their diet accordingly.

Lawnmower Blenny Tank Mates

Lawnmower Blennies usually coexist peacefully with most community fish, although they may show aggression towards other Blennies. Suitable tank mates for a Lawnmower Blenny include:

  • Blue Reef Chromis
  • Royal Gramma Basslet
  • Yellow Tang
  • Orchid Dottyback
  • Clams and other Sessile Invertebrates
  • Shrimp
  • Starfish
  • Crabs
  • Snails
  • Most Peaceful Community Fish

It’s essential to avoid housing Lawnmower Blennies with large, aggressive, predatory fish such as Sea Horses, Triggers, and Lionfish. These fish may intimidate and harass your Blenny, causing them to hide and avoid other tank inhabitants.


Breeding Lawnmower Blennies in captivity is challenging, as there are no established protocols for doing so. Most specimens available for purchase are wild-caught, and their aggression towards each other makes it difficult to cultivate them in tanks.

If you decide to attempt breeding Lawnmower Blennies, ensure you have a male and female pair and provide a large enough tank to accommodate both fish. Keep in mind that successful mating is not guaranteed, even when housing a pair together.


The Lawnmower Blenny is a charming and practical addition to any saltwater aquarium, providing both entertainment and essential algae control. By ensuring your Lawnmower Blenny receives proper care, a suitable environment, and a balanced diet, you can enjoy watching these fascinating fish thrive in your tank. If you have any further questions or concerns about Lawnmower Blenny care, feel free to reach out for guidance and advice.

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