Rock Prickleback

By David Freitas

Common Name: Rock Prickleback

Scientific Name: Xiphister mucosus

Identifying Features:

The Rock Prickleback is greenish-black in color with faint white markings around the base of its tail and light bands on its face.  It is often confused with the Black Prickleback which has similar markings radiating from its eyes except they are generally solid black markings with a light border against a uniformily black body.  The dorsal fin starts at the back of the head and goes down the length of the body merging with the caudal fin. The Rock Prickleback has very small pectoral fins and is lacking pelvic fins giving it a very eel-like appearance. They are called Pricklebacks because the dorsal fin is mostly composed of hard, spiny rays with sharp tips (the rays support the fleshy fins).


The Rock Prickleback is very shy and likes to be near shelter (rocks, shells, vegetation, etc.). Without shelter the Rock Prickleback will feel very nervous and exposed. They will swim to the nearest shelter if the cover is removed.


The Rock Prickleback lives in rocky areas mostly on the exposed coast with moderate waves. It is able to stay out of water for 17-23 hours on land if it is kept moist. The Rock Prickleback is found from south-eastern Alaska to southern California.


The Rock Prickleback eats mostly algae, but also eats small fish and crustaceans. Will also eat small chopped up fish or mussels in captivity.


Likely predators would be various shore birds, raccoons, and river otters.

Life Cycle:

The female Rock Prickleback lays her eggs in clumps under rocks and vegetation then the male coils up around the eggs and guards them until they hatch. The Rock Prickleback spawns late-winter to spring in BC and October to December in California.  The Rock Prickleback takes 4-5 years to reach maturity and can live up to 11 years. The Rock Prickleback breaths air.


David W. J. (September 24, 2007). Rock prickleback (South Sound marine life). The Olympian. Retrieved June 8, 2011 from

Froese, R. (October 6, 2010). Xiphister mucosus (Girard 1858) Rock prickleback. FishBase A Global Information System on Fishes. Retrieved June 8, 2011 from

Stephen S. (2003). Rock Prickleback Xiphister mucosus.  MSAP – Marine Species with Aquaculture Potential.  Retrieved June 8, 2011 from

Young, D. (2011) Marine life of British Columbia Identification Guide, Victoria BC

Photographs by David Freitas

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