The Lawnmower blenny (Salarias fasciatus), also known by the common names jewelled blenny, jewelled rockskipper, sailfin algae blenny, rock blenny, or algae blenny, is a benthic fish with the remarkable ability to change color, and the determination to clear patches of algae like no other.

Compatible with most fish, the lawnmower blenny plays a key part in the ocean’s ecosystem as well as makes a perfect saltwater aquarium fish.

Below we look at an overview of the Salarias fasciatus and how it fits into the ocean with regards to diet, habitat, reproduction, and all other aspects that cover this algae-hungry fish’s life.


  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Actinopterygii
  • Order: Blenniiformes
  • Family: Blenniidae
  • Genus: Salarias
  • Species: S. fasciatus

Appearance and Description

Lawnmower blennies have a similar shape to that of other blenny species, with a slender, cylindrical body that tapers towards the tail.

These neritic fish are reasonably small and generally have a compressed profile reaching lengths of between 4 and 5 inches, although they have been recorded to grow slightly larger.

Lawnmower blenny are compact bottom-dwellers that can change color
Lawnmower blenny are compact bottom-dwellers that can change color

The head of the jewelled blenny is relatively large in proportion to the rest of its body, which extends into a long dorsal fin covered in spines.

One noticeable characteristic of this fish is its unique appendages, known as cirri, which can be found above each eye. These cirri are sensory appendages and are used to detect their surroundings, much like the antenna on an insect.

Algae blennies are typically olive to dark brown with a string of dark bars and are covered in round or elongated white spots of variating sizes.

The lawnmower blenny is able to change its color according to its environment, leading it to sometimes be referred to as the oceans chameleon.

Habitat and Distrabution

Lawnmower blennies are benthic creatures (they are bottom-dwellers) and are therefore found along the seabed.

These blennies are neritic fish, meaning they prefer shallower waters, typically between 0 -26ft (0-8m), and are primarily found in tropical environments along the shallower coastal areas such as the continental shelf hiding among rocks and corals.

Algae blennies inhabit a variety of ocean habitats but are most commonly found living in coral reefs, tidal pools, lagoons, and rocky shorelines, but have also been known to adventure into the brackish waters of estuaries and mangrove forests.

Jewelled blennies make their homes among rocks and on coral reefs
Jewelled blennies make their homes among rocks and on coral reefs

The range of this benthic fish extends throughout the Indo-pacific region and can be found in the Red Sea, the east African coast, the Indian Ocean, South East Asia, and the western Pacific Ocean, including along the great barrier reef.

It is worth noting that although the lawnmower blenny has a wide distribution range, its populations are not abundant throughout the range and are more likely to be localized in specific areas.


Algae blenny, as the name suggests, feed on various types of algae as a large part of their diet; however, algae don’t make up the majority of an adult lawnmower blenny’s diet.

Using their powerful, flexible jaws and comb-like teeth, lawnmower blennies scrape the surface of hard surfaces such as rocks and coral, removing algae and other materials.

Algae blenny fish prefer shallow waters abundant with algae
Algae blenny fish prefer shallow waters abundant with algae

Although known as algae blennies, studies have found that their primary source of nutrition comes from detritus (waste or debris), with only 15% of their diet coming from plant material.

Apart from various types of algae, which include filamentous algae, and hair algae, jewelled blennies have been seen feeding on diatoms, foraminiferans, tiny crustaceans, and sand, as well as fish eggs, sponges, and small snails, on occasion.

Reproduction and Lifecycle

The lifecycle and reproduction of the Salarias fasciatus is fairly simple and goes through four basic stages within its 2 – 6 year lifespan: Courtship, the larval stage, settling, and growth into adulthood.

  • Courtship: During the reproductive season (generally when water conditions are warmer), male lawnmower blennies court females through an array of displays such as fin erecting and vibrant color changes. When a pair has formed the female will release her eggs into the water column where they are externally fertilized by the males.
  • Larval Stage: Within approximately 5 – 8 days, the eggs hatch, releasing transparent larvae that drift with the ocean currents as they develop.
  • Settling: As larvae develop into the juvenile stage, they search for a suitable substrate to settle on. This is usually algae-covered rocky areas or coral reefs.
  • Reaching Maturity: Juveniles are mostly herbivores, and after settling, they continue to feed on algae for approximately 1 – 2 years before reaching sexual maturity and repeating the cycle.

It’s worth noting that although the time of reproduction and periods of development are common, they can differ according to climate, habitat, and other external factors.

Predators and Threats

Due to their tiny size in nature, lawnmower blennies are targeted by a variety of larger fish such as groupers, lionfish, yellow soapfish, and triggerfish, as well as occasionally preyed on by invertebrates like octopi and large crustaceans.

Lionfish are among the common predators of the lawnmower blenny
Lionfish are among the common predators of the lawnmower blenny

It is also not uncommon for opportunistic sea birds to prey on these small fish.

Apart from their natural predators, jewelled blennies are threatened by many of the environmental issues that disrupt the ocean’s balance.

Habitat destruction, particularly that of coral reefs, pollution, poor water quality, and inconsistent algal growth all impact the livelihoods of this blenny and, in some cases, can eradicate them from an area.

Defense and Behavior

Lawnmower blennies are not aggressive fish. However, they are territorial and will attack/ chase away other blennies or small fish with a similar shape.

The lawnmower blenny are sociable fish but can also be territorial
The lawnmower blenny are sociable fish but can also be territorial

That said, they are very sociable, peaceful community fish when comfortable, and will establish a good relationship with other non-threatening fish.

When feeling threatened, the blenny is able to change color and will turn darker to camouflage themselves into shadows. 

Although this fish is not aggressive by nature, when threatened with no escape, it has been known to use its jaw as a defense mechanism by delivering a concussive blow to its assailant.


Are lawnmower blennies good to keep in a home aquarium?

Lawnmower blennies are great pets and will help keep algae growth in control. Although territorial, they make great tank mates, provided they have plenty of space, so ensure you check up on the minimum tank size required.

What other blenny species are worth noting?

Blennies come in many shapes, colors, and sizes, many of which seem to have little in common with each other. That said, combtooth blennies and the sailfin blenny are similar to the lawnmower blenny.

Are lawnmower blennies compatible with other tank fish?

The compatibility of the lawnmower blenny and other fish will depend on the species of fish, as well as the environment. Blennies are territorial and will attack similarly shaped fish like gobies. They are also known to harass seahorses and pipefish when kept in the same reef tank.

What can I feed my pet lawnmower blenny?

Optimal sustenance for herbivorous blennies consists of algae-infused diets, like spirulina-enhanced pellets or gel-based foods. Additionally, occasionally incorporating blanched vegetables such as peas, spinach, cucumber, and zucchini can be beneficial.

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