Lawnmower Blenny Care & Info | The Aquatic Gardener

The peaceful Salarias fasciatus is a favorite among marine aquarists for its appetite for algae. Also known as the lawnmower blenny, it doesn’t exclusively eat algae, but it certainly has enough of a taste for it that it can help you keep your tank looking nice.

Want to learn more about this bottom-dwelling underwater gardener? Keep reading for everything you need to know about keeping a lawnmower blenny!

Lawnmower Blenny Description

Appearance

Salarias fasciatus belongs to the family Blenniidae, the combtooth blennies. The species is a bit less brightly colored than some of its popular cousins, such as the scooter blenny, but we think it’s still very nice to look at! Our favorite part are the cirri, the little “antlers” on the head, which are typical for the Blenniidae.

This blenny sports a camouflage-like greenish-brown pattern, with vertical barring and a slightly darker horizontal stripe across its side. It also has a series of tiny, bright blue pinprick dots on its face.

At a maximum size of around 5”, the lawnmower blenny is not a particularly large fish. Telling the difference between males and females of this species can be rather challenging, although the females are often a bit larger and rounder.

Natural habitat

The lawnmower blenny is found throughout much of the Indo-Pacific. It occurs in the tropics and select subtropical regions, from the Red Sea and African coast all the way to the Polynesian Islands.

Here, according to marine biologists, the lawnmower blenny prefers shallow habitats interspersed with rocks, (dead) coral, and sand. It’s commonly spotted at less than 30 ft depth in estuaries, reef flats, lagoons, and similar.

The IUCN Red List considers Salarias fasciatus to be a species of Least Concern, meaning it’s not threatened in the wild. The organization bases this conclusion on the lawnmower blenny’s wide natural range and the fact that it can be very common in some places.

Lawnmower Blenny Aquarium

If you’d like to keep a lawnmower blenny, it’s important to remember that these fish really prefer to eat their natural diet of detritus, biofilm, and algae. They don’t like commercial foods that much, so it’s best to keep them in a mature tank of at least 55 gallons. The species isn’t all that active, but an aquarium this size has plenty of room for tasty bits to accumulate.

Although we’re often inclined to keep our aquariums nice and clean, this changes if you want to keep one of these blennies. Suppress the urge to scrub algae off every surface: your lawnmower blenny will do that for you.

Generally speaking, lawnmower blennies are not picky about their environment, and they do fine in standard reef parameters. However, plenty of hides are a must. These blennies are naturally prey fish, and they like to be able to dart into a cave or crevice if they happen to feel threatened while foraging.

Lawnmower Blenny Compatibility

The lawnmower blenny is a peaceful fish, just as long as its tankmates are not or do not look too much like another lawnmower blenny, that is: the species is quite territorial. Unless your aquarium is very large, it’s best not to keep any other blennies, as squabbles between them can get pretty violent.

You can combine your lawnmower blenny with most common reef fish, although it’s best to avoid the very docile species such as pipefish to prevent the blenny from bothering them. Invertebrates like crabs and shrimp are fine.

We can’t call lawnmower blennies 100% reef-safe, because they may nip at corals and clams in their pursuit of algae and other foods. According to research, this can negatively affect young corals in particular.

This being said, most aquarists don’t experience serious problems, especially if the blenny is well-fed. Let’s call them 90% reef-safe!

Lawnmower Blenny Diet

The most important aspect of keeping your blenny happy and healthy is catering to its diet of detritus, microalgae, and the like. Leaving plenty of “lawn” for it to mow is very helpful, although you’ll still have to supplement its diet. If the belly of your fish seems caved in rather than round, it’s definitely time to start trying a variety of foods to prevent it from starving!

Feed your lawnmower blenny algae-based foods specially formulated for herbivores, such as pellets or gel foods containing plenty of spirulina. You could also opt for blanched veggies like peas and spinach, or nori sheets. Keep trying and monitoring until you’re sure the fish is eating well.

Do keep in mind that blennies that are used to frequent feedings with convenient foods might be less inclined to go after algae. You shouldn’t be buying a fish to deal with an algae problem anyway, as keeping the aquarium clean is unfortunately up to you.

Tip: Dedicated lawnmower blenny owners can grow algae in a separate container by keeping rocks under strong lighting to stimulate the growth of this aquatic delicacy! Remember, they primarily like microalgae such as film and hair algae, not macroalgae (seaweed).

Breeding Lawnmower Blennies

As with many marine fish, no luck here, unfortunately. Although there have been reports of lawnmower blennies spawning in home aquariums, we’re not aware of anyone who has actually managed to raise the tiny larvae to adulthood.

Luckily, this doesn’t mean that all lawnmower blennies are wild-caught. It took a long time, but as of 2023, Biota Group has nailed the breeding process and now stocks captive-bred Salarias fasciatus. As big fans of tank-bred fish, we hope they catch on and more aquaculture farms will begin to offer them soon.

Conclusion

The lawnmower blenny is a fun and useful addition to the marine aquarium, but it can be challenging to get your fish to eat prepared foods.

Dreaming of your own reef (with or without lawnmower)? FantaSEA Aquariums can help! Just contact us with your ideas and we’ll get back to you as soon as possible.