Lawnmower Blenny

The Lawnmower Blenny, also known as the Jeweled Rockskipper or Algae Blenny, is a fascinating and useful saltwater fish renowned for its algae-eating abilities. With its mottled brown and tan coloration, high-set eyes, and comical personality, this blenny is both functional and entertaining. They perch on rocks, hopping from perch to perch while grazing on algae. These peaceful fish are excellent algae control specialists, particularly effective at eating hair algae and diatoms. Their unique appearance and behavior make them a favorite among reef aquarists.

Care Requirements

Tank Setup

Lawnmower Blennies need plenty of live rock for grazing and perching:

• Minimum 30 gallons (55+ recommended)
• Lots of live rock (20+ lbs per 10 gallons minimum)
• Various rock heights for perching
• Caves and hiding spots
• Protein skimmer
• Powerheads for moderate flow
• Heater to maintain 75-82°F
• Marine lighting to promote algae growth

Important: They spend most of their time perched on rocks grazing. The more rock surface area, the better.

Water Quality (Marine)

• Temperature: 75-82°F (24-28°C)
• pH: 8.1-8.4
• Specific Gravity: 1.020-1.025
• Ammonia/Nitrite: 0 ppm
• Nitrate: <20 ppm
• Phosphate: <0.05 ppm (some needed for algae growth)
• Calcium: 400-450 ppm
• Alkalinity: 8-12 dKH

Note: They actually prefer tanks with some algae growth for grazing. A completely sterile tank is not ideal.

Feeding

Lawnmower Blennies are specialized herbivores that primarily eat algae:

• Primary: Hair algae, diatoms, film algae from live rock
• Supplemental: Marine algae sheets (Nori)
• Spirulina-based marine pellets and flakes
• Frozen foods: Occasional Mysis shrimp
• Vegetables: Blanched zucchini, spinach

Feeding Schedule: They graze constantly on tank algae. Supplement with Nori if natural algae is insufficient.

Warning: In tanks without adequate algae, they may starve. Ensure established algae growth or provide ample Nori.

Behavior & Compatibility

Lawnmower Blennies are peaceful but can be territorial with other blennies:

• Good Tank Mates:

  • Clownfish
  • Tangs (Yellow, Blue, Kole)
  • Gobies
  • Cardinalfish
  • Dartfish
  • Firefish
  • Wrasses
  • Peaceful reef fish

• Avoid:

  • Other Lawnmower Blennies (territorial)
  • Similar blenny species
  • Aggressive fish
  • Fish that compete for the same rock perches

Personality: Comical and entertaining to watch. They hop from rock to rock, perch with a curious expression, and have great character.

Health Considerations

Common issues to watch for:

• Starvation: Most common problem - ensure adequate algae or supplemental feeding
• Marine Ich: Quarantine new fish
• Thinning: Visible weight loss indicates insufficient food

Prevention: Maintain some algae growth in the tank, provide supplemental Nori, and monitor body condition regularly.