Lawnmower Blenny: Species Profile and Care Guide

| Updated: June 14, 2023
Lawnmower blenny, algae blenny, resting on the sand in a reef tank

Suppose you are looking for a fish that can help you keep your tank clean, add some personality and charm to your aquarium, and be easy to care for. In that case, you might want to consider the lawnmower blenny (Salarias fasciatus). This fish, also known as the jeweled blenny, is popular among saltwater hobbyists for its algae-eating abilities, quirky behavior, and hardy nature. This article will tell you everything you need to know about caring for a lawnmower blenny, including its tank requirements, feeding habits, tank mates, breeding, and more.

What is a Lawnmower Blenny?

A lawnmower blenny is a tropical fish belonging to the family Blenniidae. It is native to the Indo-Pacific region, where it inhabits coral reefs and rocky areas. It gets its name from its habit of grazing on algae that grows on rocks, sand, and coral. It has a long and slender body that can grow up to 6 inches in length.

It has a large head with a blunt snout and a mouth that protrudes forward. It has small eyes that are located on the top of its head and can move independently. It has a single dorsal fin that runs along its back and a pair of pectoral fins that help it maneuver. It has a mottled brown coloration with dark spots and stripes that help it blend in with its surroundings.

Species Overview

Scientific Name
Salarias fasciatus
Common Names
Lawnmower blenny, Jeweled blenny, Algae blenny, Sailfin blenny
Indo-Pacific region
Adult Size
4-5 inches (10-13 cm)
Life Expectancy
2-4 years
Generally peaceful, but may become territorial towards other blennies, gobies or dartfish in smaller tanks
Easy, if you have plenty of algae to eat; Moderate if you don’t, due to picky eating
Minimum Tank Size
30 Gallons
Captive Breedable

Why Choose a Lawnmower Blenny?

For several reasons, a lawnmower blenny is a great choice for your saltwater tank. First, it is an excellent algae eater that can help you control unwanted algae growth in your tank. It will nibble on various types of algae, such as hair algae, green algae, brown algae, and red algae. It will also eat detritus and leftover food that might otherwise pollute your water quality. By keeping your tank clean, it will reduce the need for frequent water changes and maintenance.

Secondly, and perhaps most importantly, a lawnmower blenny is a very entertaining fish that will add fun and personality to your aquarium. It is very active and curious and will explore every inch of your tank. It will often perch on rocks or corals and watch what is going on around it. It will also interact with you and other fish in the tank. It will sometimes dart out of hiding places or jump out of the water to catch your attention. It will also display various facial expressions and body language that will make you laugh. It is a very intelligent fish that can learn to recognize its owner and even respond to feeding cues.

Thirdly, a lawnmower blenny is a hardy fish that adapts to various water conditions and environments. It can tolerate a wide range of temperature, salinity, pH, and hardness levels. It can also handle some fluctuations in these parameters without getting stressed or sick. It is not prone to many diseases or parasites and can live up to 6 years in captivity.

Lawnmower Blenny Care Guide

If you want to keep a lawnmower blenny happy and healthy in your tank, you need to provide it with the right conditions and care. Here are some of the most important factors to consider when setting up and maintaining your lawnmower blenny tank.

Tank Size

A lawnmower blenny needs at least a 30-gallon tank to have enough space to swim and graze. However, bigger is always better when it comes to saltwater tanks, as they provide more stability and diversity for your fish. A larger tank will also allow you to keep more than one lawnmower blenny if you wish, as they are not very aggressive towards their own kind unless they are breeding.

Tank Setup

A lawnmower blenny needs a tank that mimics its natural habitat as much as possible. This means you need to provide plenty of rocks, corals, caves, crevices, and hiding places where it can rest and feel secure. You also need to ensure that there is enough algae growth in your tank for your lawnmower blenny to feed on. You can add live rock or sand to your tank or introduce some macroalgae or plants that can grow under moderate lighting.

You also need to make sure that your tank has good water circulation and filtration to keep the water clean and oxygenated. You can use a powerhead or a wavemaker to create some water movement in your tank. You can also use a protein skimmer or a sump system to remove any organic waste or toxins from your water.

Water Parameters

Lawnmower blennies can tolerate a wide range of water parameters, but they prefer the following conditions:

  • Temperature: 72°F to 82°F
  • Salinity: 1.020 to 1.025 specific gravity
  • pH: 8.1 to 8.4
  • Hardness: 8 to 12 dKH
  • Ammonia: 0 ppm
  • Nitrite: 0 ppm
  • Nitrate: <20 ppm

Test your water regularly using a reliable test kit or meter and make any necessary adjustments using water conditioners or additives. You should also perform regular water changes of about 10% to 20% every week or two to keep your water fresh and balanced.

Feeding Habits

A lawnmower blenny is primarily an herbivore that feeds on algae in the wild. However, it will also accept some meaty foods occasionally as a supplement or treat. You should feed your lawnmower blenny once or twice a day with a variety of foods such as:

  • Algae-based flakes or pellets
  • Spirulina or nori sheets
  • Frozen or live foods such as brine shrimp, mysis shrimp, bloodworms, or copepods
  • Fresh vegetables such as zucchini, cucumber, lettuce, or spinach

You should soak any dry foods in some tank water before feeding them to your lawnmower blenny to make them softer and easier to digest. You should also clip any seaweed or vegetables onto the side of the tank using a veggie clip or suction cup so that your lawnmower blenny can graze on them throughout the day.

You should avoid overfeeding your lawnmower blenny as this can cause health problems such as obesity or constipation. You should only feed it as much as it can eat in a few minutes and remove any uneaten food from the tank.

Tank Mates

A lawnmower blenny is generally peaceful towards other fish in the tank as long as they are not too similar in appearance or behavior. It will usually ignore most other fish unless they try to compete with them for food or space.

Some good tank mates for a lawnmower blenny are:

  • Clownfish
  • Tangs
  • Gobies
  • Damsels
  • Chromis
  • Wrasses
  • Cardinals
  • Blennies (of different species)

Some bad tank mates for a lawnmower blenny are:

  • Angelfish
  • Butterflyfish
  • Triggerfish
  • Puffers
  • Lionfish
  • Eels
  • Crabs
  • Shrimps

These fish are either too aggressive, too territorial, too predatory, or too nippy for a lawnmower blenny and might harass it or harm it.

Before adding them to your tank, you should always research any potential tank mates and ensure they are compatible in size, temperament, diet, and water parameters.


Lawnmower blennies are not easy to breed in captivity, requiring specific conditions and triggers to spawn successfully. However, some hobbyists have managed to do so by providing them with optimal water quality, plenty of food, suitable hiding places, and stable mates.

Lawnmower blennies are sexually dimorphic, meaning that males and females look different. Males are larger than females and have more prominent dorsal fins with spines along their edges. Females are smaller than males and have smoother dorsal fins without spines.

These adorable little algae munchers are monogamous, forming a pair bond with one mate for life. The pair will defend their territory from other fish and prepare a nesting site under a rock or coral where they will lay their eggs.

The female will lay about 1000 eggs at a time which the male will fertilize externally by releasing his milt over them. The male will then guard the eggs until they hatch after about 5 days.

The fry will emerge from the eggs as tiny larvae that will drift in the water column for about 2 weeks before settling on the bottom of the tank, where they will start feeding on algae and microorganisms.

The fry are difficult to raise as they require very clean water and a constant food supply of live foods such as rotifers, phytoplankton, copepods, etc. You should also provide them with plenty of hiding places where they can feel safe from predators.

You should separate the fry from the parents and other fish in the tank as soon as possible after they hatch into their own rearing tank, where you can monitor their growth and development more closely.

Effortless Care Tips for Lawnmower Blennies

Keeping a lawnmower blenny is not very difficult if you follow some simple tips that will make your life easier and your fish happier. Here are some of them:

  • Provide your lawnmower blenny with plenty of algae to eat. This will keep it healthy and satisfied and reduce the need for supplemental feeding. You can also grow some algae in a refugium or a separate tank and transfer it to your main tank periodically.
  • Keep an eye on your lawnmower Blenny’s weight and body condition. You might need to adjust its diet if it looks too thin or too fat. A healthy lawnmower blenny should have a round belly, not a bloated one.
  • Watch out for signs of stress or illness in your lawnmower blenny. If it stops eating, becomes lethargic, hides more than usual, or develops any abnormal symptoms such as spots, sores, or parasites, you should take action immediately. You should quarantine it in a separate tank and treat it with the appropriate medication or remedy.
  • Avoid adding any fish or invertebrates that might compete with or harm your lawnmower blenny. You should also avoid overcrowding your tank or changing the tank setup too often as this might stress out your lawnmower blenny and make it more vulnerable to disease or aggression.
  • Enjoy your lawnmower Blenny’s personality and antics. You should interact with it regularly and observe its behavior and expressions. You can also train it to recognize you and respond to your commands by using food as a reward.

Final Thoughts

A lawnmower blenny is a perfect choice for your saltwater tank if you are looking for a fish that can help you keep your tank clean, add some personality and charm to your aquarium, and be easy to care for. In this article, we have told you everything you need to know about lawnmower blenny care, including its tank requirements, feeding habits, tank mates, breeding, and more.

Thank you for reading, and happy fishkeeping!

More Saltwater Fish

If you’re interested in learning about other saltwater fish, check out:

Or browse our saltwater fish articles here!

Shane Elliot Author Image
Shane Elliot

Shane Elliot is a pet lover and a coral enthusiast. He has been keeping saltwater aquariums for over ten years and enjoys sharing his knowledge and expertise with other hobbyists. He writes about coral care, fish compatibility, aquarium equipment, and more. He also covers topics related to other animals, such as dogs, cats, horses, and reptiles. Shane works as a freelance writer and editor when his menagerie of pets allows it.

Read More

Leave the first comment

More From BuzzPetz

Before you go - You'll want to check out these articles!
[ultimatemember form_id="4648"]

Already a member?

Login Here

[uwp_register id="3" title="register"]

Not a member?

Register Here