Slimy Snailfish, Liparis mucosus

Slimy Snailfish, Liparis mucosus. Fish caught from coastal waters off Santa Cruz, California, January 2023. Length: 6.1 cm (2.4 inches). Catch, photograph and Identification courtesy of Vince Golder, Santa Cruz, California.

The Slimy Snailfish, Liparis mucosus, is a member of the Snailfish or Liparidae Family, and is known in Mexico as baboso mucoso. The snailfish comprise a large and diverse family with three hundred thirty-four members that have been placed into twenty-nine genera. Globally, there are sixty species in the Liparis Genus.

The Slimy Snailfish has an elongated body that varies in color from a uniform gray to brownish to red, and occasionally with dark stripes. They have a tadpole-like head with miniscule eyes and tiny teeth. Their anal and dorsal fins have long bases but are not continuous with the caudal fin. They have a fairly unique body shape with modified pelvic fins that form a small sucking disc placed far forward below the eyes. Their gill slit extends to the front of the upper pectoral fin rays. Their anal fin has 22 to 24 rays; their caudal fin is narrow and rounded; their dorsal fin has 28 to 30 rays. They do not have scales.

The Slimy Snailfish are found in intertidal area at depths up to 18 m (60 feet). They reach a maximum of 12.7 cm (5.0 inches) in length. They feed on small benthic crustaceans, mollusks, polychaeta worms, and other small invertebrates. Snailfish will use their pelvic disk to attach to a rock while they wait patiently for passing prey to swim by. They have sensory pores in their head and can feel vibrations when food is near. They attached themselves to rocks with their sucker and eat by sucking in all of the water in front of them and filtering out the food. They consume amphipods, clams, copepods, crustaceans, Daphnia salina, echinoderm larvae, invertebrates, mysis, snails, worms, and zoanthids. They lay only a few large eggs. The young resemble tadpoles.  The Slimy Snailfish is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, diet, growth, habitat, longevity, movement patterns, and reproduction.

The Slimy Snailfish is a resident of Mexican waters of the Pacific Ocean but has a very limited distribution being found only north of San Carlos, Baja California Sur, along the central and northwest coasts of the Baja Peninsula.

The Slimy Snailfish is straightforward to identify due to its characteristic shape and cannot be confused with any other species.

The Slimy Snailfish has not been formally evaluated from a conservation perspective. They are seldom seen by humans and are of limited interest to most.