Lawnmower Blenny
Salarias fasciatus
The Lawnmower Blenny, also known as the Algae Blenny or Jewelled Blenny, is one of the most recognisable and entertaining algae-grazing fish in marine aquariums. Its mottled pattern of earthy browns, creams and dark bands, accented by delicate blue spots and distinctive fleshy projections above its eyes, provides excellent camouflage among natural reef rockwork.
What the Lawnmower Blenny may lack in brilliant colouration, it more than makes up for in personality. With its oversized, watchful eyes and almost comical facial expressions, this curious fish spends much of its day perched on rocks, exploring crevices and making short movements between its favourite grazing areas.
Native to shallow reefs and coastal waters throughout the Indo-Pacific, the Lawnmower Blenny naturally grazes on algae and the complex layer of microorganisms and organic material growing across submerged surfaces. Its specialised comb-like teeth allow it to scrape food from rockwork, making it a potentially valuable addition to an established marine aquarium.
Although well known for helping to manage nuisance algae, the Lawnmower Blenny is not a guaranteed solution to every algae problem. Individual feeding preferences vary, and the fish requires a reliable supply of natural grazing material or suitable supplementary foods to remain healthy.
Generally peaceful towards unrelated fish, this species can become territorial with other blennies and competing algae grazers. It is best maintained individually in a mature aquarium with plenty of rockwork and natural feeding opportunities.
With its curious nature, distinctive appearance and fascinating grazing behaviour, the Lawnmower Blenny brings both personality and natural activity to a carefully maintained reef aquarium.
Feeding Notes
Lawnmower Blennies are specialised algae and aufwuchs grazers, naturally feeding on the mixture of microalgae, diatoms, biofilm and organic material found on reef surfaces.
A mature aquarium with established natural algae growth provides valuable grazing opportunities throughout the day. However, natural grazing alone should not be relied upon to meet all their nutritional requirements.
Supplement their diet regularly with marine algae such as nori, high-quality spirulina-based pellets or flakes, and other suitable marine herbivore preparations. Some individuals may also accept small amounts of frozen mysis or other meaty foods, although vegetable-based nutrition should remain the foundation of their diet.
Offer supplementary food daily, adjusting feeding frequency and quantity according to the fish's body condition and available natural grazing. Ensure the fish is actively accepting an appropriate diet and maintaining a healthy, rounded abdomen.
Important: Although Lawnmower Blennies are valued for helping control nuisance algae, their effectiveness varies between individuals and algae types. They often prefer soft film algae and short growth rather than established long hair algae or other persistent nuisance species.
A lack of suitable food can lead to gradual weight loss and starvation, particularly in new or exceptionally clean reef aquariums. Never assume that the presence of algae alone guarantees adequate nutrition.
Aquarium Setup Notes
Provide a mature, stable marine aquarium of at least 200 litres with extensive established rockwork, natural grazing surfaces, sheltered crevices and sufficient space for the fish to establish its territory.
Lawnmower Blennies spend much of their time perched on rocks, moving between grazing areas and retreating into small caves or holes when disturbed. An aquascape with varied rock surfaces and multiple sheltered resting places encourages natural behaviour.
A well-established aquarium is particularly important. This species relies heavily on natural algae and biofilm, making newly established or exceptionally clean systems less suitable unless the fish is reliably accepting appropriate supplementary foods.
Moderate, varied water movement is suitable, provided calmer areas are available for resting and grazing. Normal reef aquarium lighting is appropriate, with shaded retreats among the rockwork.
A secure aquarium lid or mesh cover is strongly recommended. Lawnmower Blennies can jump when startled, particularly during territorial disputes or after introduction to a new environment.
Monitor the fish's body condition regularly. A noticeably sunken abdomen, reduced grazing activity or progressive weight loss may indicate inadequate nutrition and should be addressed promptly.
Compatibility Notes
Lawnmower Blennies are generally peaceful towards unrelated marine fish and can coexist successfully with suitable community species, including clownfish, cardinalfish, peaceful wrasses and many gobies.
However, they can be territorial towards other blennies, similarly shaped bottom-dwelling fish and competing algae grazers. Aggression may be particularly noticeable in smaller aquariums or when food and grazing surfaces are limited.
Best kept singly in most home aquariums. Multiple Lawnmower Blennies may compete aggressively for territory unless maintained as a compatible pair in a sufficiently large and carefully structured system.
Exercise caution when combining this species with other algae-grazing fish, particularly those competing for the same limited food resources. Adequate aquarium space, natural grazing material and supplementary feeding are essential.
Reef safe with caution: Lawnmower Blennies are generally compatible with established reef aquariums and do not normally feed on healthy coral tissue. However, occasional individuals may nip small-polyped stony corals, fleshy coral tissue or clam mantles, particularly when appropriate grazing foods are insufficient.
Most ornamental reef invertebrates are usually left undisturbed, although individual behaviour can vary and compatibility cannot be guaranteed.
Their regular habit of perching on corals may also cause temporary polyp retraction or irritation in particularly sensitive colonies.
With suitable feeding, plenty of established rockwork and carefully selected tankmates, the Lawnmower Blenny can be a rewarding inhabitant of a mature mixed reef aquarium.