Algae Lawnmower Blenny - Salarias fasciatus

Medium (2.25-3.5")

$31.99

Algae Lawnmower Blenny - Salarias fasciatus

$31.99

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Goes well with:

Diet

Pellets Nori Algae Flakes

Min Tank Size 30 gallons

Temperament Peaceful

Reef Safe Yes

Care & Diet Feeding, nutrition, and best practices.

Diet Type: Herbivore

The Sailfin Algae Blenny primarily feeds on algae, making it an excellent addition for controlling algae growth in the aquarium. Supplement its diet with high-quality marine algae or spirulina-based foods. Offer a variety of algaes including nori occasionally. Feed small amounts twice daily, ensuring it has access to natural algae on live rock. Avoid overfeeding to maintain water quality and prevent health issues.

Pellets Nori Algae Flakes

Behavior Temperament, activity level, and interactions.

Temperament: Peaceful

Tank & Aquascape Tank requirements and aquascaping tips.

Min Tank Size: 30 gallons
Max Size: 5.5 inches
Care Level: Easy
Origin: Philippines

Compatibility Tank mates, aggression, and introduction order.

Temperament: Peaceful
Reef Safe: Yes

Blenny Reef Safe Herbivore

Reef & Health Reef safety, common issues, and prevention.

Reef Safe: Yes
Care Level: Easy

FAQs Answers to the most common questions.

My Sailfin Algae Blenny ignores hair algae but constantly grazes on the glass and rocks. Is this normal, and how can I encourage it to eat problematic algae like filamentous or turf algae?

Yes, it’s normal. Sailfin Algae Blennies (Salarias fasciatus) often prefer microfilms of diatoms and biofilm on rocks and glass over long filamentous hair algae. They’ll usually nibble at the bases of hair algae rather than the strands themselves. To encourage more focused grazing on problem algae: (1) Avoid over-cleaning rocks and glass so there’s always a natural film for them to graze; (2) Reduce other food sources so they’re a bit hungrier, but not starved; (3) Manually pull long hair algae to short stubble—blennies are more likely to graze the short, new growth; (4) Maintain stable nutrients (nitrate and phosphate in a low-but-detectable range) so film algae regrows and keeps them active and healthy. They are not a cure-all for hair algae, but a support to overall algae control.

My Sailfin Algae Blenny is constantly perched on the highest rock and flaring at new fish, especially other bottom dwellers. Is this aggression a problem, and which tank mates should I avoid?

Sailfin Algae Blennies are territorial around their chosen “grazing zone” and perch, especially in smaller tanks or when rockwork is sparse. Mild chasing and flaring is normal, but persistent harassment (bitten fins, fish refusing to come out) is an issue. Avoid housing them with other blennies of similar shape (lawnmower, starry, etc.), small gobies that use similar perches (like some watchman and sand perch gobies), and timid benthic fish in nano systems. Provide multiple rock structures with separate sight lines so each fish can hold its own area. In tanks 55 gallons and larger with complex rockwork, their aggression usually becomes a manageable, low-level territorial behavior.

My Sailfin Algae Blenny was very active for months but is now losing weight even though there’s still algae in the tank. What specific foods and feeding methods are best to prevent starvation in this species?

These blennies can slowly starve in “too clean” or low-film tanks, or when the remaining algae is not their preferred type. Supplement their diet with: (1) Dried nori (seaweed) clipped near their favorite perch—tear it into smaller strips they can rasp at; (2) Spirulina-based sinking pellets or wafers, broken into small pieces and placed near their grazing areas; (3) Frozen herbivore blends with high algae and spirulina content; (4) Occasional high-quality, small meaty items (like finely chopped mysis) for variety, but keep them primarily on plant-based foods. Feed small amounts 2–3 times daily, aiming for a slightly rounded belly. If they’re shy, pre-soak pellets and place them in crevices where the blenny already grazes.

My Sailfin Algae Blenny repeatedly scrapes itself on the rocks and substrate, but its skin looks clean and it still eats. How do I tell normal “perching and squeezing” behavior from a real health problem like parasites?

These blennies often wedge themselves tightly into holes and crevices and will “squeeze” or rub along rocks while grazing, which can look like flashing. Normal behavior: they continue to graze constantly, show no white spots or dust, no frayed fins, normal breathing, and only occasional rubbing associated with feeding and moving around. Concerning behavior: frequent, frantic flashing against objects, hanging near surface or heavy breathing, clamped fins, visible white spots, velvety sheen, or cloudy patches. If you see several of those signs together, suspect parasites (marine ich or velvet) and move the fish to a properly cycled quarantine tank for diagnosis and treatment. If it’s only occasional rubbing and the fish is active and eating aggressively, it is likely normal behavior for this species.

My Sailfin Algae Blenny has developed a pale “beard” or discoloration around the mouth and chin area. Is this a common injury from grazing, or does it indicate a bacterial or fungal problem?

Mouth and chin wear is fairly common because Sailfin Algae Blennies constantly rasp hard surfaces with their specialized teeth. Mild, even lightening of the chin area with no fuzzy growth, no open sores, and normal feeding is usually simple abrasion. However, if you see: (1) Cottony or fuzzy growth; (2) Redness, swelling, or crater-like ulcers; (3) Difficulty grabbing food or a sudden drop in appetite; then a bacterial or fungal infection is more likely. In that case, move the fish to a quarantine tank with clean, stable water and treat with an appropriate broad-spectrum antibiotic (for bacterial) or antifungal as indicated, while reducing very rough or sharp rock surfaces in the display tank to limit future abrasion.

You will receive a fish SIMILAR in design and size to the fish in the photo. This is NOT a WYSIWYG fish.

Algae Lawnmower Blenny – Salarias fasciatus

The Algae Lawnmower Blenny, also known as the Sailfin Blenny or Jewelled Blenny, is a characterful saltwater fish with a mottled olive, tan, gray, and brown body marked by irregular bands, pale spots, and occasional blue highlights. Branched cirri above the eyes, expressive facial features, and an elongated dorsal fin give this bottom-dwelling marine aquarium fish a distinctive appearance. Its natural camouflage allows it to blend easily into live rock and reef rubble.

Native to the Indo-Pacific, Salarias fasciatus ranges from the Red Sea and East Africa to Samoa, north to the Ryukyu Islands, and south to the Great Barrier Reef and New Caledonia. It inhabits shallow reef flats, lagoons, seaward reefs, and algae-rich rubble areas, where it lives primarily as a solitary grazer. Adults reach approximately 5.5 inches.

Its active grazing, unusual perching behavior, and engaging personality make it a popular addition to mature reef aquariums and peaceful fish-only aquariums. Although it can help manage certain algal films and filamentous growth, it will not consume every nuisance-algae species and should not be treated as a substitute for proper nutrient control and aquarium maintenance.

Quick Care Guide

Care Level: Easy to Moderate
Minimum Tank Size: 30 gallons
Temperament: Peaceful
Diet: Herbivore / Detritivore
Reef Safe: Yes
Region: Indo-Pacific, from the Red Sea and East Africa to Samoa
Scientific Name: Salarias fasciatus

Tank Requirements

Provide a mature aquarium with abundant live rock, established algal growth, and numerous caves, ledges, and crevices. The Algae Lawnmower Blenny spends much of its time perched on rockwork before making short movements to graze nearby surfaces. Arrange the aquascape so the fish has several secure retreats and broad areas of exposed rock available for feeding.

A sand or fine-gravel substrate is suitable, although no specialized substrate is required. Moderate, well-distributed water movement and good oxygenation are appropriate, with calmer areas available among the rocks. The aquarium should be well established rather than newly cycled, as sterile rockwork may not provide enough natural grazing material.

Use a securely fitted lid or mesh cover. This species may jump when startled, pursued, or newly introduced. Long-term housing should provide enough rock surface and territory for its adult size rather than relying only on aquarium volume.

Diet and Feeding

In nature, Salarias fasciatus feeds by scraping algae and associated organic material from rocks, coral rubble, and other hard surfaces. Captive specimens commonly graze microalgae, soft filamentous growth, and biofilm, but individual feeding preferences vary. They should not be expected to eliminate all forms of hair algae, cyanobacteria, or other nuisance growth.

Supplement natural grazing with spirulina-based flakes, marine herbivore pellets, frozen algae blends, finely chopped marine algae, and small pieces of nori. Occasional mysis shrimp, enriched brine shrimp, or mixed marine frozen foods may be accepted, but algae-rich foods should remain the foundation of the diet.

Offer one or two small meals daily and monitor body condition closely. Some individuals adapt readily to prepared foods, while others depend heavily on naturally growing algae. A blenny with a noticeably pinched abdomen may not be receiving enough nutrition, even when it appears to graze throughout the day.

Temperament and Tankmates

The Algae Lawnmower Blenny is generally peaceful toward unrelated community fish but may become territorial around its preferred cave and grazing area. Suitable tankmates include clownfish, cardinalfish, gobies, peaceful wrasses, dwarf angelfish, and other non-predatory marine species.

Keep one specimen in most aquariums. It may behave aggressively toward other lawnmower blennies, combtooth blennies, or similarly shaped bottom-dwelling fish. Competition may also develop with tangs and rabbitfish that graze the same rock surfaces, particularly when food or territory is limited.

Avoid highly aggressive tankmates that may prevent it from feeding or repeatedly force it away from the rockwork. Newly introduced specimens may remain hidden until they become familiar with the aquarium.

Reef Compatibility

The Algae Lawnmower Blenny is considered reef safe. It does not normally consume healthy stony corals, soft corals, anemones, clams, snails, or ornamental shrimp. Its grazing is generally directed toward algae and biofilm growing on rocks, aquarium walls, and other hard surfaces.

The fish may perch on coral colonies or scrape algae from frag plugs and exposed coral bases. This activity is usually harmless, although loosely mounted fragments may be disturbed. Decorative macroalgae may also be grazed.

Water Parameters

Temperature: 75–80°F
Specific Gravity: 1.024–1.026
pH: 8.1–8.4
Alkalinity: 8–12 dKH

Maintain consistent salinity, good oxygenation, and stable water quality. Stability is more important than repeatedly adjusting the aquarium to reach one exact reading.

Common Considerations

Provide mature rockwork: Established algae and biofilm are important for natural grazing.
Do not rely on algae control alone: This species does not consume every nuisance-algae type.
Monitor body condition: Constant grazing does not guarantee that the fish is receiving enough nutrition.
Use caution with other blennies: Territorial disputes are common with similar-looking or competing grazers.
Secure the aquarium: A fitted lid helps prevent jumping when the fish is startled.