It’s stick or swim for these fishes.

Most snailfishes (family Liparidae) live near the seafloor, riding the currents that sweep along the bottom. A hungry snailfish may swim against the currents to hover above the seafloor while searching for snacks buried in the mud. In some species, frilled fins probe the seafloor for hidden morsels of food. 

Snailfishes make their homes in a variety of ocean habitats, from shallow tide pools to deep-sea trenches. In fact, a snailfish holds the record for the deepest-dwelling fish. Remote cameras deployed by researchers studying the Izu-Ogasawara Trench off Japan filmed a white snailfish in the genus Pseudoliparis at the remarkable depth of 8,336 meters (27,349 feet)—more than five miles deep!

Scientists have described more than 450 different species of snailfish worldwide. Snailfishes have a large head, a jelly-like body covered in loose skin, and a narrow tail. Many have fins on their belly modified into a disk that can hold on tight to rocks, seaweed, or even larger animals like deep-sea crabs for shelter. Most are small and feed on tiny invertebrates.

MBARI has encountered more than a dozen snailfish species in our explorations of the deep waters of the Northeastern Pacific. We see the blacktail snailfish (Careproctus melanurus) most frequently. This pink species with a distinctive dusky tail is common on the muddy slopes around Monterey Canyon. In the canyon’s deepest stretches, the snowy-white abyssal snailfish (Careproctus ovigerus) is more abundant. 

While most snailfishes live near the seafloor, the tadpole snailfish (Nectoliparis pelagicus) lives in the midwater, an expanse of open water deep below the surface, yet far above the seafloor. We occasionally come across this little snailfish drifting in the water column, curled into a doughnut shape.

Many deep-living snailfishes are rarely seen, so the footage filmed by our robotic submersibles provides valuable data about their appearance and behavior. MBARI’s advanced underwater technology has helped our collaborators describe two new species—the arbiter snailfish (Careproctus kamikawai) from local seamounts and the bumpy snailfish (Careproctus colliculi) from the abyssal seafloor offshore of Central California. Snailfishes are among the fish families with the most new species being described. We suspect there are dozens more out there waiting to be discovered.

Our observations have revealed the mysterious lives of deep-sea snailfishes. MBARI’s work helps resource managers and policymakers understand how threats like climate change, mining, and pollution affect deep-sea animals and ecosystems. What we learn can help guide their decision-making about the future of the ocean.