Lawnmower Blenny (Salarias fasciatus)

 

• Small fish safe: ✅ Yes

• Small invert safe: ⚠️ Generally

• Coral safe: ⚠️Reports of coral nipping, but usually as a result of algae around coral polyps

• Minimum tank size: 114 liters (30 gallons)

• Adult size: Up to 14 cm (5.5 inches)

• Diet: Herbivorous, primarily feeding on algae

• Be aware of: May become territorial towards similar species; requires a well-established tank with ample algae growth; known to jump, so a secure lid is essential

 

Appearance and Coloration

The Lawnmower Blenny exhibits a mottled tan to brown coloration with darker bands and spots, providing effective camouflage against rocky substrates. Its elongated body and continuous dorsal fin are characteristic features, complemented by expressive eyes that add to its endearing personality. Some individuals can slightly adjust their coloration to blend with their surroundings.

 

Natural Habitat and Behavior

In the wild, Salarias fasciatus inhabits shallow coastal regions, reef flats, and lagoons at depths of up to 30 feet. These fish are commonly found perching on rocks or hopping across the substrate as they graze on algae. While generally peaceful, they may exhibit territoriality towards conspecifics or similar-looking species in confined spaces.

 

Tank Requirements and Water Parameters

• Minimum Tank Size: 30 gallons (114 liters)

• Water Parameters:

• Temperature: 23°C – 27°C (73°F – 81°F)

• pH: 8.1 – 8.4

• Specific Gravity: 1.020 – 1.025

• Aquascaping: Plenty of live rock to encourage natural algae growth and create hiding spots.

• Lighting: Moderate to high lighting to support algae growth.

• Water Movement: Moderate flow, mimicking their natural coastal habitats.

Maintaining stable water conditions and a mature tank environment is crucial, as fluctuations can negatively impact their health.

 

Diet and Feeding

Lawnmower Blennies are primarily herbivorous and rely on a steady supply of algae:

• Natural Diet: They graze on filamentous algae, diatoms, and detritus in the wild.

• Captive Diet: Best kept in mature tanks with sufficient natural algae. If algae is lacking, supplementation is needed:

• Dried seaweed (nori) secured on a veggie clip

• Spirulina-based foods

• Herbivore pellets or flakes

Some individuals may refuse prepared foods, so introducing them into a well-established tank with natural algae is ideal.

 

Compatibility and Social Structure

• Territoriality: May become aggressive towards other blennies or similar-looking fish, particularly in smaller tanks. Best kept singly unless in a large system.

• Tank Mates: Compatible with most peaceful community fish but may harass very timid species.

• Reef Compatibility: Generally reef-safe but may nip at small-polyped stony corals and clam mantles if underfed.

 

Important Considerations

• Tank Maturity: Best suited for well-established aquariums with natural algae growth.

• Jumping Behavior: Known to jump out of open tanks, so a secure lid is necessary.

• Health Monitoring: Ensure adequate nutrition, especially if algae levels decline.

With the right conditions, the Lawnmower Blenny is an excellent and engaging addition to a marine aquarium, helping with natural algae control while providing entertaining behaviours to observe.