Lawnmower Blenny: Care Guide, Breeding, Tank Size & Disease

Lawnmower Blenny Overview

The Lawnmower Blenny is a very fascinating, comical saltwater fish for an aquarium. Apart from its humorous nature, it controls algae growth in the tank. Most hobbyists keep the fish for entertainment. In the process of enjoying its many comical displays, they also realize the tank’s algae growth is minimal.

Several other names know the fish, including Jeweled Rock Skipper, Algae Blenny, Jeweled Blenny, and Sailfin Blenny. Several households have adopted the droll sea animal as a home pet to keep them entertained as it never runs out of great performances.

Information Chart Lawnmower Blenny
Scientific Name: Salarias Fasciatus
Family: Blenniidae
Care Level: Easy to Intermediate
Temperament: Peaceful towards other fish, except other Blennies
Color: Brown, Green, or Cream
Lifespan: 2 to 5 years
Size: 4 to 6 inches
Diet: Herbivore
Minimum Tank Size: 40 gallons
Temperature: 72 to 78 degrees F
Water Conditions: pH 8.1 to 8.4
Tank Mate Compatibility Peaceful community if given space

Lawnmower Blenny Appearance

Lawnmower Blenny Fish

Considered a peaceful fish with a great personality, this little sea animal has unique features. One of the features is their brown body color with white spots at a given section of its profile. You can also spot some green on the fish. The dark color helps it in camouflage. If it patches on a brown rock, it becomes complicated to notice it. It has a long yet slender body.

Other features of Lawnmower Blenny are a single dorsal fin that extends the whole length of its body. They have a blunt head with bulging eyes perched at the top. On the face are scattered blue dots that form some kind of artwork around the eyes. Extending from the pupils outward are white stripes that create a radial type of pattern.

The Lifespan of Lawnmower Blenny

The typical lifespan of a Lawnmower Blenny is 2 to 5 years. Of course, their lifespan differs on factors such as the species in question. It also depends on their tank and water conditions.

Lawnmower Blenny Size

The typical Lawnmower Blenny grows to 4 inches on the lower end and 6 inches for larger specimens. The quality of care they receive will directly impact their growth.

Natural Habitat and Origin

Lawnmower Blenny refers to a member of the Blenniidae family. It was first discovered in 1786 by Bloch as Salarias Fasciatus. The reason why it is named that is because of its habit of grazing on algae.

It is native to the East African Indian Ocean, Samoa, Red Sea, Great Barrier Reef, and the Islands of Micronesia. It obtained its name from its ability to clear algae from around its habitat.

Lawnmower Blenny enjoys swimming in shallow waters with little or no other sea life in its natural habitat. They swim as a group around rocks. In the wild, this fish lives in shallow reefs and lagoons. These places have lots of space in the coral rubble, sponges, stones, and many areas for algae to grow. They are primarily solitary and are found at depths up to 260 feet in the water.

Lawnmower Blenny Care & Tank Set-Up

The Lawnmower Blenny needs a huge tank that can provide a large area for algae growth. For this reason, the following tank requirements should be able to meet its needs:

Lawnmower Blenny Tank Size and Specifications

Optimum Tank Size for Lawnmower Blenny

Lawnmower Blenny Tank Size and Specifications

The recommended tank size for Lawnmower Blenny is 40 gallons, 48″x12″x16″. Of course, the fish will appreciate a bigger tank, as space crunches will give rise to aggression.

Tank Shape for Lawnmower Blenny

A tank with an enormous surface area is best for Lawnmower Blennies, as well as for algae growth. Even though the minimum requirement is 40 gallons, it is advisable to go in for a bigger size than that.

Filter Type

You will need a vital filter outlet since the Lawnmower Blenny needs a moderate to high water flow. Invest in a good quality filter to ensure that the water quality is optimum for this fish. A high-quality canister filter with carbon filtration media will do the job of providing good water quality. You can also go in for air or a water pump.


The best substrate for a Lawnmower Blenny tank would be sandy, as these are bottom dwellers. Use a fine sandy substrate for the fish to dig. Using fine sand will reduce the risk of injuries while they try to dig in.

How many Lawnmower Blenny fish can you keep in a 40-gallon tank?

Only one mated pair of Lawnmower Blenny can be kept in a 40-gallon tank. They are particular about having their own space. Having other Blennies in the tank with them is a considerable risk unless you increase your tank size to 100 gallons at least. For every pair that you add to the tank, consider increasing the size by another 40 gallons. It is advisable to keep Lawnmower Blennies in big community tanks, so they have a place to roam around.

Water Parameters for Lawnmower Blenny

Water Parameters for Lawnmower Blenny

Water Temperature

The ideal water temperature for Lawnmower Blenny is between 72 to 78 degrees F. When you change the tank water, make sure that the new water also has the same temperature as the old one. Lawnmower Blenny is not very sensitive to temperature changes, but you should try and establish a constant with them.

Water Flow Rate

Lawnmower Blenny prefers a moderate to high water movement.

pH Level

The perfect water pH level for Lawnmower Blenny is pH 8.1 to 8.4. They are very particular about changes in pH and salinity.

Water Hardness

The water hardness for a Lawnmower Blenny tank should be 8 – 12 dKH. Since Lawnmower Blennies are saltwater fish, they need a constant salinity of 1.020-1.025.

You must change out at least a quarter of the tank’s water once a week to clean conditions. Remember that Lawnmower Blennies will fall sick if too many algae and other floating matter are in the water. This practice will create unsafe conditions for your underwater habitat. It is essential to monitor the state of your aquarium’s water regularly. Use a reliable water testing kit to make sure that the water conditions are ideal.

Lawnmower Blenny Tank Landscape

The most important thing to make sure that Lawnmower Blennies are happy in their tank is to have a lot of algae growth in the tank. Remember that Lawnmower Blenny is a jumpy fish, so a tank lid is a must. Here are some more tips to decorate and set up the perfect tank for these jumpy and active fish:

Lawnmower Blenny Tank Landscape

Best Plants for Lawnmower Blenny Tanks

Live and natural plants are a must-have for Dwarf Cichlid tanks. They need lush vegetation around them to hide and to eat too. Some great plants are java moss, java fern, cryptocoryne. Try and stick with plants that do well with a sandy bottom and can grow in saltwater. They mainly eat algae so that they will leave the plants alone. Do not populate your tank with too many plants, though! Lawnmower Blenny loves to explore, so be sure to give them enough space.

Worst Plants for Lawnmower Blenny Tanks

You should avoid plants with large, spindly mops as they leave very little space for the fish to roam about in the tank. Also, you should avoid plants that cannot grow on a sandy substrate or restrict the fish’s movement.

Decorations for Lawnmower Blenny Tanks

The key to recreating the natural habitat for Lawnmower Blennies is to have a natural tank setup. Rocks are the best decoration for a Lawnmower Blenny tank as it gives them room to jump around. Try to recreate a coral reef environment by adding live rocks and pieces of driftwood. Position them in a way that gives them space to hide inside.

Lighting for Lawnmower Blenny Tanks

There is no need for extra lighting for a Lawnmower Blenny tank. They are used to hiding under the cover of rocks and plants. Avoid bright sunlight hitting the tank, though. However, the live plants in the tank will need light to grow. For this, the natural lighting hitting the tank is enough. If the tank is in a dark corner, then provide an LED light bulb around it.

Feeding Lawnmower Blenny

Best Diet for Lawnmower Blenny

The fish is considered herbivorous and will mainly feed on algae. Most hobbyists add it to the aquarium to demolish algae build-up. The fish never disappoints in this. If the tank has no sufficient algae growth, you can purchase some form of it (algae pellets) as an alternative. This practice will prevent it from starving. Add vegetables like lettuce and spinach to the tank. You can chop these into tiny pieces that are easy to digest.

Nori is another marine algae supplement that You can add to its diet. Keep a bit of processed fish food, too, just in case. Although it tends to appreciate algae more when this is lacking, it settles for processed foods. To be successful, introduce processed food to it as soon as it gets into its new environment. This practice will help it adjust to the new diet.

Try to avoid stuffing too much food into the tank if there is no cleaner fish to clear away remnants. Most fish develop ich as a result of wasted food staying longer inside the tank. If possible, adopt a cleaner fish that will clear away any leftovers. Keep a close look at the fish. If there are signs of depreciating body size, try to observe the diet keenly.

While feeding, be careful with the tank lid as they are known to jump quite highly. If not properly fed, the fish claws at corals and may nip clams.

How often should you feed Lawnmower Blenny?

Lawnmower Blenny should typically be fed a few times in the week, once a day. It depends on the already available food. Lawnmower Blennies are true to their name. They will constantly eat algae off of the rocks in the tank. If they have enough algae to munch on, then do not provide them with excessive food.

Lawnmower Blenny Behaviour and Temperament

Is Lawnmower Blenny lone or societal?

The fish is relatively friendly. However, they may pick a fight with congeners, conspecifics, and other same species of fish. The reason for this is when the tank is small with a massive number of tank-mates. Even though Lawnmower Blennies are community fish, they often live alone due to this incompatibility.

It may also turn aggressive to sea horses or pipefish. If they share the same tank, check them regularly if they are compatible. If you witness any signs of aggressiveness, you should separate them. They are known to recognize regular faces and may reward it with a few theatrics.

One of their names is Rock Skipper because they jump or hop from one rock to another. They tend to live around the live rock or sand substrate in the case of a tank.

Lawnmower Blenny Tank Mates

Ideal Lawnmower Blenny Tank Mates

Lawnmower Blennies are good tank mates for other fish as long as you provide them with enough space of their own. Surprisingly for them, they can live peacefully with most community fish, except their species!

Unless you have a tank more prominent than 100 gallons, you can only keep one pair of Lawnmower Blenny (one male and one female) together.

Bad Tank Mates for Lawnmower Blenny

Be careful not to place Lawnmower Blennies in the same tank as other algae-eaters or other Blennies. Keep in mind that in a tank of fewer than 100 gallons, you can only keep a pair together (preferably one male and one female). They will tend to compete for food and fight each other to death otherwise. Enormous, aggressive fish are also a no-no. Some tank mates to avoid for a Lawnmower Blenny tank are:

  • Angels
  • Saltwater Tangs (such as Yellow Tangs, etc.)
  • Pipefish
  • Sea horses
  • Toadfish
  • Triggers
  • Lionfish (such as Dwarf Lionfish, etc.)
  • Groupers
  • Frogfish
  • Anglers
  • Damselfish
  • Large Dottybacks

Breeding Lawnmower Blenny

There are no records of Lawnmower Blenny breeding in captivity. It is challenging to get the conditions right at a home aquarium.

Lawnmower Blenny fish spawn between April and June when the rising temperature acts as a trigger for them.

In the wild, they are substrate spawners. That means the females lay their eggs on the substrate in empty shells, and the males fertilize them. Males also guard the eggs until they hatch. The eggs stay in the substrate until they are ready to hatch. The larvae are planktonic and live in shallow waters.

In a tank environment, you will need to gradually raise its temperature to 78 degrees F to breed them successfully. If a pair mates, you will follow the same process. You will have to watch out for the fry not to eat the other tank mates. It will only happen after the protection of the male ends.

It is advisable to use a separate breeding tank for this process if you do attempt it.

Lawnmower Blenny Breeding Level – Hard

Lawnmower Blenny Sexual Dimorphism?

To distinguish between male and female Lawnmower Blenny, we must observe their size. Like a large number of other fish species, lawnmower blenny males and females look alike. Telling the difference between males and females is a difficult task. However, males are said to be bigger than their female counterparts. The anal fins may also betray a slight difference. The male has more prominent anal spines packed with plenty of flesh as opposed to the female.

Lawnmower Blenny Common Diseases and their Treatment

Lawnmower Blenny is resilient. They are immune to most marine diseases. When they appear ill, make sure that you do not treat them with any medicines unsuited to scaleless fish. A common illness might be:

Ich or White Spot Disease

White Spot Disease causes respiratory problems in the fish. They will show restless behavior, but most importantly, white spots on the body of the fish. This illness will go away once you meet the ideal water conditions. Other symptoms will include lethargy, and the fish will stop eating. Since this is a common disease, you can also opt for over-the-counter medications to treat it quickly.

Parasitic infections

Parasitic infections are common in unclean water. If there is any leftover debris in the tank, it will cause bacteria that contribute to these infections. The best thing to do is to isolate the affected fish and treat them first. If you maintain hygiene and care in the tank, these diseases will not occur.

Apart from looking out for any common diseases, stress reduction, offering plentiful space to them, and providing a clean tank are the best things that you can do to care for your Lawnmower Blenny.

Facts about Lawnmower Blenny

  • Lawnmower Blenny has many names: Rock Skipper, Algae Blenny, Jeweled Blenny, and Sailfin Blenny.
  • They are saltwater fish and are used as a clean-up crew since they eat the algae growing in the tanks.
  • They are also referred to as ‘chameleons of the aquarium’ because they blend in with their surroundings.
  • They also have large orbital eyes, like a lizard or an iguana.
  • Lawnmower Blennies are less brightly colored than their cousins.
  • They are often preyed on, so it is important to provide them with hiding spots when they feel threatened.
  • A fascinating feature about them is that they leave kiss marks on the glass while eating algae!

Is Lawnmower Blenny Right For You?

Author’s Note: There is no reason not to get a Lawnmower Blenny pair for your tank. Not only are they hardy, but you also need minimum care. This makes them perfect for beginners in the aquarist industry. Even though they are less colorful than their saltwater companions, they are jovial and have entertaining personalities! However, they would not be suited for your home aquarium if you have a reef tank, as it will make them more territorial, and they will not co-exist well.


What do you feed a Lawnmower blenny?

In the wild, Lawnmower Blenny eats algae and other plants. Your tank needs to have plenty of algae growth to feed them properly. Also, give them some prepared foods which marine herbivores can eat without a risk.

Will a Lawnmower Blenny eat hair algae?

Yes, this Blenny will consume any type of algae, including hair algae.

Are Lawnmower Blennies hardy?

Yes, they are very hardy. The Lawnmower Blennies do not fall victim to any common saltwater diseases. But to keep them healthy, pay attention to their water requirements. Make sure that tank hygiene is maintained.

How long do Lawnmower Blennies live?

These fish live for 2 to 5 years on average. But if you meet the water conditions and the fish eat healthy food, they can have a life expectancy of up to six years.

Which are the best fish to combine with a Lawnmower Blenny in a tank?

Only place more fish with Blennies if your tank is more extensive than 50 gallons. It is not advisable to have any other fish in a Lawnmower Tank that is smaller than that. This essentially means you can only keep a pair together because they are territorial and aggressive with other Blennies, especially. Only one mated team can stay peacefully in a smaller tank.

Where does the Lawnmower Blenny sleep?

Lawnmower Blenny sleeps at the bottom of the tank. They find holes in rocks towards the ground and hide inside crooks.

Does Lawnmower Blenny Eat Seaweed?

The Lawnmower Blenny species do not usually eat a lot of seaweed. But, this is not a dangerous thing for them to eat. If you are trying to get your Blennies accustomed to a new tank with algae still growing, this can be helpful! Some seaweed and nori flakes will help them start to graze. They can also eat seaweed as a supplement to their regular algae diets. Remember not to overfeed seaweed to them, though!


The Lawnmower Blenny is a delightful little fish with a beautiful personality. Lawnmower Blennies are curious and intriguing fish that express themselves simply by staring at you. This appealing species will immediately become a favorite of yours. These fish are ideal for beginners with a quiet reef tank because they are easy to care for and can help maintain the tank free of hair algae. The only limitation to keeping them is their compatibility with tank mates. While you need a slightly bigger tank to keep them, you need to make sure they are okay with their tank mates. Otherwise, there will be a lot of harassment and fights in the tank.

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