Lawnmower Blenny: Your Ultimate Guide to Maintaining a Healthy Aquarium

Meet the Lawnmower Blenny, a charming and unique marine fish known for its algae-eating abilities and whimsical personality. Scientifically called Salarias fasciatus, this fish is a favorite among saltwater aquarium enthusiasts for its hardworking nature and entertaining behaviors.

In this article, you’ll get to know more about the Lawnmower Blenny, from its appearance to its ideal habitat and care requirements. By understanding its fascinating characteristics, you’ll be better equipped to provide a healthy and fulfilling life for your new aquatic friend. So, let’s begin our journey into the world of the Lawnmower Blenny and learn what makes this fish so special.

Species Overview

Lawnmower Blennies (Salarias fasciatus) are good-natured, diligent cleaner fish that inhabit saltwater tanks and control algae growth. These captivating creatures are part of the Blenniidae family, which includes all combtooth blennies.

They’re commonly known as Jeweled Blennies, Sailfin Blennies, Algae Blennies, or Jeweled Rock Skippers. Your Lawnmower Blenny can be expected to live for about an average lifespan of 3-6 years, depending on the care provided in their aquarium.

These fish are mostly solitary and are found in various locations such as Africa and Oceania. They contribute significantly to maintaining a clean tank environment by feeding on algae, making them an invaluable addition to your saltwater aquarium.

Here’s a brief overview of the Lawnmower Blenny characteristics in a table format:

Property Lawnmower Blenny
Scientific name Salarias fasciatus
Common names Jeweled Blenny, Sailfin Blenny, Algae Blenny, Jeweled Rock Skipper
Distribution Africa, Oceania
Size Up to 5 inches
Lifespan 3-6 years
Diet Herbivore (mainly algae)
Temperament Peaceful
Minimum tank size 30 gallons
Temperature 72-78°F (22-26°C)
pH 8.1-8.4
Water hardness 8-12 dKH
Care level Moderate
Filtration/Water Flow Medium
Water type Saltwater
Breeding Egg layer
Breeding difficulty Challenging
Compatibility Reef-safe, community tanks

So, if you’re considering adding a Lawnmower Blenny to your aquarium, remember to provide them with the necessary care and proper tank set-up for them to thrive and contribute to a healthier environment for the other inhabitants in your aquarium.

Natural Habitat and Distribution

Habitat and Range

The Lawnmower Blenny (Salarias fasciatus) is a fascinating species that can be found in various marine habitats. As a reef dweller, it prefers shallow waters with plenty of rocks and hiding spots. You’ll mostly find them in areas rich in algae, as it’s their primary food source. They inhabit a wide geographic range, including the Great Barrier Reef, the Red Sea, the Indian Ocean, Micronesia, East Africa, and Samoa.

Great Barrier Reef

In the Great Barrier Reef, Lawnmower Blennies thrive among the diverse coral formations and rocky reefs. Here, they play an essential role in maintaining the health of the ecosystem by consuming algae.

Red Sea

The Red Sea’s crystal-clear waters and unique coral reefs provide an ideal environment for the Lawnmower Blenny. They help keep the algae population under control, ensuring a healthy balance in the underwater ecosystem.

Indian Ocean

In the Indian Ocean, the Salarias fasciatus can be found along the coral reefs that have ample hiding spots and rock formations. The abundance of algae in this region makes it a perfect home for this helpful fish species.


The vibrant and colorful coral reefs of Micronesia house a variety of marine life, including the Lawnmower Blenny. Feeding on algae, they contribute to maintaining the stability and diversity of the coral ecosystem.

East Africa

Off the coast of East Africa, in the Indian Ocean, the reefs and coastal waters provide a suitable habitat for the Lawnmower Blenny. The warm temperatures and rich variety of algae support their diet and wellbeing in this region.


In the South Pacific, Samoa’s pristine coral reefs with their abundance of algae form an ideal environment for the Salarias fasciatus to thrive and play a role in preserving the reef’s overall health.

By understanding and appreciating the natural habitat and distribution of the Lawnmower Blenny, you can gain a deeper respect for this unique species and their crucial contribution to the preservation and conservation of our world’s marine ecosystems.

Physical Appearance

In this section, you’ll learn about the unique physical features of the Lawnmower Blenny.


The Lawnmower Blenny has a captivating appearance, blending shades of brown and green with different patterns. This fish is known for its ability to change color and intensity based on its mood or surroundings, similar to a chameleon. You’ll also notice spots and stripes on its body, adding to its striking look.


Lawnmower Blennies have a modest size, generally reaching a maximum length of around 5 inches. This makes them a perfect fit for most saltwater tanks. Of course, their size may vary slightly depending on factors such as diet and living conditions.


Equipped with a large dorsal fin, Lawnmower Blenny uses it as an essential tool for both stability and propulsion. Its anal fin, found on the underside of its body, lends additional support and balance for this agile swimmer.


One of the key attractions of the Lawnmower Blenny is its efficiency in cleaning up your tank. Thanks to its specialized teeth designed for scraping and feeding on algae, this fish becomes an essential addition to your aquarium in keeping it neat and tidy.

Behavior and Personality

Peacefulness and Aggression

Lawnmower Blennies are generally peaceful fish, perfect for a community saltwater tank. They have a unique personality and can be quite entertaining to watch, as they happily graze on algae. However, they can exhibit some aggression, especially towards other blennies and similar-shaped fish. To avoid conflicts, it’s best to have only one Lawnmower Blenny in your tank.


These fish are known to be territorial but mostly when it comes to their living space and food supply. You’ll often see them carefully guarding their favorite algae-covered rocks. To minimize territorial behaviors, ensure your tank has an adequately sized area for them to claim as their own and plenty of algae to graze on.

Pair Formation

When it comes to mated pairs, Lawnmower Blennies are not usually monogamous fish, making it difficult to form a mated pair. However, if you manage to find a compatible partner, they can coexist without too much trouble. Just make sure there’s enough space and resources to satisfy both fish.

Remember to always monitor your Lawnmower Blenny’s behavior and adjust your tank setup as needed, ensuring harmony among all tank inhabitants.

Diet and Feeding

Algae Consumption

Your lawnmower blenny will mostly graze on algae in your aquarium. This includes green hair algae, filamentous green microalgae, and diatoms. It’s important to have a mature aquarium with plenty of algae growth for them to eat. In case algae isn’t sufficient, you can supplement their diet with dried seaweed and spirulina.

Invertebrates and Sponges

While algae is their primary food source, they may also feed on tiny invertebrates and sponges. These additional sources of food help to diversify their diet and ensure that they get all the nutrients they need.

Additional Food Sources

Lawnmower blennies can also consume detritus present in the tank, as it is a natural part of their diet. Detritus, made up of decomposed organic material, is an essential component for your blenny’s overall feeding needs. However, it should not be relied on for the majority of their nutrition.

Remember, keeping a variety of food sources will help maintain your lawnmower blenny’s health and well-being.

Aquarium Care

Ideal Tank Size

To ensure the optimum environment for your Lawnmower Blenny, it is essential to provide a tank that is ideally at least 30 gallons in size. This will give them ample space for swimming and exploring in their new home. Additionally, a larger tank also makes it easier to maintain stable water parameters.

Water Parameters

Maintaining suitable water parameters is crucial for your Lawnmower Blenny’s health and well-being. Aim to keep the following parameters in your saltwater aquarium:

  • Temperature: 72-78°F (22-26°C)
  • Salinity: 1.020-1.025 specific gravity
  • pH: 8.1-8.4
  • Nitrate: <20 ppm
  • Ammonia: 0 ppm
  • Nitrite: 0 ppm

Perform regular water tests to monitor these parameters, and perform partial water changes as needed to maintain a stable environment.

Substrate and Rock Setup

Creating a comfortable and functional environment for your Lawnmower Blenny involves providing substrate and live rocks for them to explore and graze on. Opt for a sandy substrate, as it allows them to dig and search for food. Arrange the live rocks in a way that creates plenty of hiding places and surfaces for algae to grow. This will not only keep your fish entertained but also help to keep the tank clean by encouraging algae growth, which the blenny will graze on.

Providing Food

Lawnmower Blennies are predominantly herbivorous fish, with a diet primarily consisting of microalgae. It’s essential to provide a varied diet, including marine algae, spirulina, and high-quality marine flakes or pellets to ensure they receive proper nutrition. You can also encourage natural algae growth on the live rocks in your reef tank to supplement their diet and provide a more natural environment.

Remember to feed your Lawnmower Blenny in small amounts, 2-3 times per day, to keep them healthy and active.

Compatibility and Tank Mates

Reef Safety

Lawnmower blennies are considered to be reef safe as they do not harm corals and polyps in your reef tank. They mainly graze on algae, which helps keep your tank clean and healthy. However, always monitor your blenny’s behavior to ensure the safety of your corals and coral polyps.

Suitable Tank Mates

When adding tank mates to your aquarium with a lawnmower blenny, focus on choosing peaceful and non-aggressive species. Some suitable tank mates include:

  • Goby species: Watchman gobies and neon gobies make excellent companions for lawnmower blennies due to their similar size and temperament.
  • Other peaceful fish: Lawnmower blennies can get along well with other peaceful and non-aggressive fish species.

Remember to consider the size, temperament, and habitat requirements of tank mates to ensure compatibility with your lawnmower blenny.

Potential Problems

Although lawnmower blennies are generally compatible with a variety of tank mates, there are some potential problems to be aware of:

  • Similar body composition: Watchman gobies and lawnmower blennies may fight due to their similar body compositions. If you have a larger tank, such as 120 gallons, the chance of fights might decrease due to the increased space.
  • Predators: Be cautious when adding larger, more aggressive species, like lionfish. They might see your lawnmower blenny as prey.

To prevent compatibility problems, carefully choose tank mates for your lawnmower blenny and monitor their interactions to ensure a peaceful coexistence in your aquarium.

Breeding and Reproduction

Breeding Lawnmower Blennies can be quite challenging, as there are no established protocols for breeding them, and most specimens available are wild-caught. To attempt breeding, you’ll need to introduce a male and female into a large enough tank. Identifying their genders can be tricky though, as males and females look similar. However, males have more prominent anal fins with extended spikes and flesh.

In the wild, Lawnmower Blennies typically spawn between April and June. Increased water temperatures encourage mating, but simply housing a pair together doesn’t guarantee success, as Blennies are selective about partners. If breeding occurs, the female lays sticky, fertilized eggs that attach to a surface or substrate in the tank.

The male guards the eggs until they hatch, and unlike some other fish species, Lawnmower Blennies do not eat their eggs or fry. However, the young Lawnmowers are vulnerable to tank mates, so you should keep an eye on them.

Though it may be tempting, due to the species’ aggression toward each other and ease of capture in the wild, cultivating them in tanks is generally not justified. Some experts recommend establishing a separate breeding tank, but it can be a significant investment given the low odds of successful breeding.

Common Health Issues

As a Lawnmower Blenny enthusiast, it’s crucial for you to be aware of common health issues affecting these fascinating creatures. One of the most prevalent diseases among Lawnmower Blennies is Marine Ich. This condition is caused by the parasitic organism Cryptocaryon irritans, which thrives in poor water conditions.

To identify Marine Ich, look for white spots on your Blenny’s body, which is the most telling symptom. Affected fish may also exhibit fatigue, lethargy, appetite loss, and breathing difficulties. If you observe these signs, take action immediately. Start by isolating the affected Blenny in a separate tank and treating it with an over-the-counter anti-parasitic medication.

While treating the infected Blenny, don’t forget to check the water conditions in the main tank. Restoring proper parameters is essential for the well-being of your Blenny and the other inhabitants of your aquarium. Regular water quality checks and maintenance can help prevent the occurrence of Marine Ich and ensure a healthy environment for your Lawnmower Blenny.

Frequently Asked Questions

Are lawnmower blennies hard to keep?

Lawnmower blennies are considered relatively easy to care for, making them a good choice for both beginner and experienced aquarium hobbyists. To keep your lawnmower blenny healthy, you’ll need to maintain stable water conditions, including a temperature between 72-78 degrees Fahrenheit and a pH of 8.1-8.4.

What do lawnmower blennies eat?

Lawnmower blennies primarily feed on algae. They are known as detritivores, meaning they graze on various types of micro-algae, such as diatoms and hair algae, which naturally grow in a marine aquarium. It is essential to ensure they have enough algae to consume to stay healthy.

Is Lawnmower Blenny Reef Safe?

Yes, lawnmower blennies are considered reef safe. They are a peaceful fish species that tend to get along well with other tank inhabitants and do not typically cause any damage to corals or other invertebrates.

Do lawnmower blennies eat hair algae?

Lawnmower blennies are particularly fond of hair algae. In fact, they got their name because of their grazing behavior, which resembles a lawnmower moving across a lawn. They help keep hair algae growth in check in your aquarium, making them a beneficial addition to most saltwater tanks.

Is Lawnmower Blenny aggressive?

Lawnmower blennies generally have a peaceful nature and are non-aggressive towards other tank mates. However, they can be territorial at times, especially towards other blennies or fish species that share similar habitats. It’s essential to provide enough hiding spaces and watch their behavior to ensure harmony in the tank.

What tank size do lawnmower blennies need?

A minimum tank size of 40 gallons is recommended for a lawnmower blenny. They can grow up to 4-5 inches in length, and a larger tank helps provide adequate space for them to swim and graze on algae. Always check your tank’s compatibility and capacity before adding any new fish species to your aquarium.