TankBud

Lawnmower blenny

Salarias fasciatus

Also known as Algae blenny, Sailfin blenny, Jeweled rockskipper, Sailfin algae blenny

SaltwaterFish

Lawnmower blenny (Salarias fasciatus)
Dirk Godlinski · CC BY-SA 3.0

Care at a glance

Temperature
72–79°F
22–26°C
pH
8.1–8.4
Adult size
5.1 in
13 cm
Minimum tank
29 gal
110 L
Temperament
Mostly peaceful
Social behavior
Solitary
Own kind
One per tank
Tankmates
With caution
Swim level
Bottom
Diet
Omnivore
Difficulty
Easy
Breeding
Hard
Rarity
Very common
Reef safe
Reef safe with caution
Family
Blenniidae
Origin
Indo-Pacific reefs and lagoons from the Red Sea and East Africa to the western Pacific

Overview

The lawnmower blenny is an algae-grazing blenny that perches on the bottom of a saltwater tank. It is easy to keep in a mature tank with plenty of algae.

Did you know

The lawnmower blenny mows film algae off rock all day, one patch at a time. It is one of the few marine fish people add specifically as a cleanup crew for nuisance algae. A really clean tank starves it, so the fish meant to fix an algae problem needs one to eat.

Caring for the lawnmower blenny

Keep the lawnmower blenny in 29 gal (110 L) or more, in a mature tank with lots of live rock. It is a bottom-oriented perching fish, not an open-water swimmer, so a good growth of algae matters more than swimming length. A well-established tank with real algae growth is close to a requirement.

Hold stable marine water at 72 to 79°F (22 to 26°C) and a pH of 8.1 to 8.4. Its main food is algae and biofilm. Supplement that with dried marine and blue-green algae, such as nori and spirulina, plus the occasional meaty food.

Keep one per tank, since it squabbles with its own kind and with other algae-grazing blennies unless the tank is very large. It is mostly peaceful toward unrelated fish.

It is usually safe with corals, so it rates reef safe with caution. A hungry blenny in a tank without enough algae has been reported to nip clam mantles and pick at SPS and fleshy coral polyps. Keep it well fed. It has been bred in captivity only rarely, and breeding it is hard.

Good to know

The lawnmower blenny is a combtooth blenny in the family Blenniidae, also sold as the algae blenny, sailfin blenny or jeweled rockskipper. It has a blunt-nosed, frog-like face, feathery cirri over the eyes and a mottled brown pattern that shifts to match the rock. It scrapes algae and detritus with rows of fine, comb-like teeth, which is where the family name comes from. Nearly all fish in the trade are wild-caught.

In the wild

Lawnmower blennies live on shallow reef flats, rubble zones and lagoon bottoms across the Indo-Pacific. Their range runs from the Red Sea and East Africa to the western Pacific. They perch on rock and graze film algae off hard surfaces.

Common questions

What size tank does a lawnmower blenny need?

A lawnmower blenny needs at least 29 gal (110 L). It spends most of its time in the bottom.

What temperature and pH does a lawnmower blenny need?

A lawnmower blenny is comfortable at 72–79°F (22–26°C) with a pH of 8.1–8.4.

What does a lawnmower blenny eat?

A lawnmower blenny eats mostly algae and biofilm. Supplement that with dried marine and blue-green algae, such as nori and spirulina, plus the occasional meaty food.

How big does a lawnmower blenny get?

An adult lawnmower blenny reaches about 5.1 in (13 cm).

Related species