Monkeyface Prickleback Facts

Monkeyface Prickleback Profile

The monkeyface prickleback, also known as the monkeyface eel and blenny eel, is a nearshore fish with an elongated, eel-like body. These fish belong to the prickleback family, Stichaeidae, of which there are 17 species off the coast of California alone.

The monkeyface prickleback may be found from Baja California, Mexico to southern Oregon, USA along the Pacific coast. It is most widespread off the coast of central California and rare south of Point Conception.

They are infamous for their amusing name, which is derived from their monkey-face-like appearance.

Monkeyface Prickleback Facts

Monkeyface Prickleback Facts Overview

Habitat: Tide pools or shallow rocky areas
Location: Eastern Pacific, from southern Oregon, USA to northern Baja California, Mexico
Lifespan: Up to 18 years
Size: Up to 30 inches long (76.2 cm)
Weight: About 6 lbs (2.3 kg)
Color: Light brown to dark green with rust-colored markings, black strips behind eyes
Diet: Carnivorous as a juvenile (zooplankton, copepods, amphipods, isopods), herbivorous as an adult (algae)
Predators: Birds (egrets and mergansers), cabezon, grass rockfish, marine mammals, humans
Top Speed: 1 kph (0.6 mph)
No. of Species:
Conservation Status:
Not evaluated

They are often found in the intertidal zone, with depths ranging from the upper intertidal to a recorded depth of 80 feet.

Monkeyface prickleback prefers rocky intertidal regions with plenty of crevices, boulders, and algal cover, such as high and low tide pools and shallow subtidal habitats with rocky reefs and kelp beds.

Behind the eyes are two distinctive black streaks, and spines along the back that give it its name. Adults have a bumpy ridge at the top of their skull, a round snout, a protruding bottom jaw, and large lips.

The monkeyface prickleback has a consistent light brown to dark green color, with many rust-colored markings on the sides of its body.

According to existing data on sexual maturity ages, both sexes begin to mature in their third or fourth year. The monkeyface prickleback may grow to be 30 inches (76.2 cm) long and weigh up to 6.1 pounds (2.3 kg).

Females are oviparous, laying their eggs on stony subtidal substrates. Internal fertilization occurs from January to May, with the peak spawning period occurring from February to April. 1

Monkeyface prickleback are known to guarding their nests, although it is unknown if the egg mass is guarded by the female, male, or both sexes. The length of the larvae at hatching is also unknown.

Interesting Monkeyface Prickleback Facts

1.    The monkeyface prickleback is not a true eel

Though it is often referred to as an eel due to its long, eel-like body, the monkeyface prickleback is not an eel at all. In fact, this fish come from the family Stichaeidae, which consists of 45 species of fish, all with elongated, slightly compressed bodies. 2

monkeyface prickleback eel like body

2.    Their long bodies allow them to hide in small crevices

These secretive crevice-dwelling fish like to keep squished beneath boulders and in kelp beds. They are masters of camouflage, using their lengthy bodies to find a suitable opening and slip right in. 

3.    They switch from a carnivorous to an herbivorous diet as they age

As it grows, the diet of the monkeyface prickleback transforms from carnivorous to herbivorous. They mostly feed on zooplankton as juveniles. When they reach adulthood, however, they become nearly entirely herbivorous.

They are notoriously picky eaters as well. The fish survives solely on the specific algae found in the tidepools where it resides. Over sixty varieties of algae have been identified as food sources in the tidepools where they live. Despite this diversity, they appear to feed on only eight to ten different red and green algae types. 3

4.    They are serious homebodies

The monkeyface prickleback is considered a resident species, travelling no more than 15 feet from its home rock to feeding and foraging areas. It appears to have a tiny home range of few meters and is most active during flooding tides.

Because monkeyface pricklebacks reside near the coast, tidepoolers turning over rocks may occasionally see one dart away. Experienced tidepoolers understand the importance of relocating rocks so that fish can return to their homes.

5.    As long as they are kept moist, the monkeyface prickleback can survive out of water for up to 35 hours

Unlike most fish, the monkeyface prickleback has adapted to breathe both on land and in the water. This has a lot to do with where they choose to live.

As the tide goes out, monkeyface pricklebacks stay in their homes. This will often leave them out of water for a period of time until the tide returns. During low tide emergence, these intertidal fish are able to produce enough CO2 to equal their metabolic output through air to help them survive. 4

6.    They grow slower than most fish

Monkeyface prickleback grow slowly compared to other fish, particularly after the

 first few years of life. A fish typically matures around three years old, when it hits approximately 12-inches in length. By the time it is 15 to 17 years old, it will only be about 24-inches long.

7.    A females can lay up to 46,000 eggs at a time

Females spawn eggs from early January through the beginning of May. The small eggs are deposited as a ball-shaped mass on rocks in tidepools. The mass is about 3 inches in diameter and can hold up to 46,000 eggs.

8.    Monkeyface prickleback is quickly becoming a culinary delicacy

Monkeyface pricklebacks are viewed as a model candidate for long-term aquaculture. The fish’s vegetarian diet allows it to be fed on feed that does not rely on fishmeal and fish oil. Using plant-based food components helps minimizes pollution while also saving money.

They are also known to be incredibly tasty. Historically, monkeyface pricklebacks have been obtained using the poke-poking—a method, which involves inserting a long bamboo pole strung with a wire leader and a tiny, baited hook on the end into possible crevices or cracks in the rocks at low tide. 5

9.   They are in the children’s book ‘You’re Called What?’ by Kes Gray

The infamous and hilarious children’s book is about silly, weird and fun amimal names, and the silly-named Monkeyface Prickleback is one of the stars of the book, alongside the Blue-Footed Booby and the Tasselled Wobbegong.

You're Called What? Monkeyface Prickleback

Monkeyface Prickleback Fact-File Summary

Scientific Classification

Kingdom: Animalia
Phylum: Chordata
Class: Teleostei
Order: Perciformes
Family: Stichaeidae
Genus: Cebidichthys
Species Name:
Cebidichthys Violaceus

Fact Sources & References

  1. Marshall, W., & WYLLIE ECHEVERRIA, T. (1991). Age, length, weight, reproductive cycle and fecundity of the monkeyface prickleback (cebidichthys violaceus). CALIFORNIA FISH AND GAME.
  2. Mecklenburg, C. W. (2004). Annotated Checklist of Fishes. California Academy of Sciences, 35.
  3. Horn, M. H., Murray, S. N., & Edwards, T. W. (1982). Dietary selectivity in the field and food preferences in the laboratory for two herbivorous fishes (Cebidichthys violaceus and Xiphister mucosus) from a temperate intertidal zone. Marine Biology, 67(3), 237-246.
  4. Martin, K. L. (1993). Aerial release of CO2 and respiratory exchange ratio in intertidal fishes out of water. Environmental biology of fishes, 37(2), 189-196.
  5. Ugly fish fits bill for sustainable aquaculture – Aquaculture North America. Retrieved May 17, 2022.