Moonwalking fish: armored searobins walking on the seafloor

In August 2026, a team of Chinese marine researchers published observations of a deep-sea fish that walks across the ocean floor sideways like a crab — and even moonwalks backward. No other fish species has been seen doing this.

The discovery

The species, Scalicus engyceros, is an armored searobin in the family Peristediidae. It was first described in 1872 and was already known to "walk" using its thick, stiffened fin rays, but the new footage from the South China Sea captured several novel behaviours never before recorded in a fish:

• Sideways scuttling, like a shrimp or crab, using its pelvic fins as legs.
• Backward moonwalking — shuffling rearward across the seabed.
• Jerky leaps when startled or threatened.

The observations came from two submersibles operating at depths between 350 and 500 metres: the manned vehicle Shenhaiyongshi ("deep-sea warrior") and the remotely operated vehicle Haiqin. The team also sighted six individuals of a second species, Peristedion liorhynchus, in an underwater canyon.

"These walking fish harbor far more novel behavioral and evolutionary adaptations than previously assumed." — Han Tian, Sun Yat-sen University, lead author of the study published in Ocean-Land-Atmosphere Research, September 2026 [1]

Anatomy of a walker

The fish is literally armored in bony plates covering its body. Other distinguishing features include:

• Branched barbels on the snout that look like a garden rake. These act as both tactile and chemical sensors, sweeping across the seabed to "sniff out" food and navigate obstacles.
• Two fan-like pectoral fins used for balance while walking.
• Stiffened fin rays in the pelvic fins, which function as legs.
• Large eyes that may be degenerating — the fish showed little response to the submersible's lights. At hundreds of metres down, vision matters less than mechanical and chemical sensing.

The researchers noted that the barbels "seem awkward because it appears inconvenient for walking," raising questions about whether the function of these appendages has been co-opted for a different sensory role in the dark benthic environment.

Evolutionary context

Based on existing taxonomy, the three peristediid species observed in this study share a common ancestor that lived around 60–70 million years ago. Their walking adaptations evolved to handle extreme conditions — roughly 40 atmospheres of pressure at those depths.

There are a dozen or so other fish known to walk on land (such as the mudskipper) or walk on the seafloor (including the blind cave angel fish), but none combine the full set of behaviors seen in S. engyceros. The sideways shuffle, backward movement, and leaping put it in a league of its own.

Why it matters

Most of the deep ocean floor remains unmapped and unobserved. The fact that a fish first described 154 years ago still has undiscovered behaviours is a reminder of how little we know about life at the bottom of the sea. As Tian puts it:

"Ultimately, this research will reshape scientific perceptions of deep-sea biodiversity and reveal how extreme marine environments drive the emergence of one-of-a-kind biological structures and behaviours unseen in any other aquatic organism on Earth."

The footage was published in Ocean-Land-Atmosphere Research on September 1, 2026 [2].

Sources

[1] Han Tian et al., "Dynamic ambulational behaviors in armored searobins (Peristediidae) from the South China Sea," Ocean-Land-Atmosphere Research, September 2026.

[2] ScienceAlert coverage, "Scientists filmed an alien-looking fish moonwalking across the seafloor," August 31, 2026. https://www.sciencealert.com/scientists-filmed-an-alien-looking-fish-moonwalking-across-the-seafloor

Edited: 2026-09-06 · Verified: unverified

Written from publicly reported science journalism and peer-reviewed research. The moonwalking behaviour was specifically observed in new 2026 submersible footage.