A rare deep-sea anglerfish was found alive near the ocean surface off Tenerife in the Canary Islands in late January 2025, giving researchers an extraordinary opportunity to observe an adult specimen in broad daylight far above its usual deep-water habitat.
The fish was identified as Melanocetus johnsonii, commonly known as the humpback anglerfish or black seadevil. Members of the marine research group Condrik Tenerife encountered the animal while returning from a pelagic shark research trip about two kilometers off the island's coast.
Marine biologist Laia Valor told EFE that she noticed a dark object in the water that did not look like plastic or other debris. The team then spent several hours observing and documenting the weakened fish.
An exceptionally rare surface encounter
The researchers described the encounter as potentially the first recorded observation of a living adult M. johnsonii at the surface in broad daylight under these circumstances. That wording is important: deep-sea anglerfish have previously been documented through collected specimens and deep-sea observations, while larvae can occur much closer to the surface.
According to FishBase, M. johnsonii is a mesopelagic and bathypelagic species distributed through tropical and temperate parts of the world's oceans. Records extend across a broad depth range, although the species is typically associated with deep water.
The Tenerife specimen was already in poor condition when the team encountered it. Valor told EFE that it survived for only a few hours. After it died, the fish was collected so that it could be preserved and studied rather than lost at sea.
Why was a deep-sea fish at the surface?
Researchers did not establish a cause for the animal's unusual ascent. Possible explanations were discussed after the sighting, but there was no evidence sufficient to determine whether illness, an environmental condition, an oceanographic process, or another factor brought this particular fish toward the surface.
Valor emphasized that the observation was highly unusual and isolated, telling EFE that there could be many possible explanations and that the team simply did not know why the animal was there.
That uncertainty makes it inappropriate to treat the sighting as evidence of a broader environmental change on its own. A single unusual animal encounter can generate scientific questions, but establishing a cause requires additional evidence.
A predator adapted to darkness
Deep-sea anglerfish are best known for the specialized lure extending from the head of females. The structure, called an esca, can produce light through a relationship with bioluminescent bacteria, helping the fish attract prey in environments where sunlight is absent or extremely limited.
The Smithsonian Ocean explains that the anglerfish's luring apparatus evolved from a modified dorsal-fin ray. Its light-producing tip can draw prey close enough for the predator to capture it with its large mouth and specialized jaws.
Melanocetus johnsonii also shows pronounced differences between the sexes. FishBase records females reaching substantially larger sizes than males, a characteristic common among several groups of deep-sea anglerfish.
The Tenerife specimen entered a museum collection
After the fish died, it was transferred to Tenerife's Museum of Nature and Archaeology, known as MUNA. The museum later confirmed through taxonomic examination that the specimen was Melanocetus johnsonii and added it to its scientific collection.
In a February 2025 statement, the museum said the fish had been found close to the sea surface off southwestern Tenerife and noted that it already held another abyssal specimen dating from 2017.
The story did not end with preservation. In June 2025, MUNA announced that researchers had subjected the specimen to a non-invasive CT scan. The examination produced high-resolution cross-sectional images intended to help scientists study its internal anatomy and look for visible signs of disease or other pathology.
The museum said the imaging work was carried out with specialists including Alejandro Suárez Bonnet of the Royal Veterinary College and Alejandro de Vera Hernández of the Tenerife Museum of Natural Sciences. The analysis offered researchers another opportunity to investigate an animal that is rarely available for examination in such recently collected condition.
The extraordinary footage therefore became more than a brief glimpse of a deep-sea animal in an unexpected place. The preserved specimen now provides scientists with material for further study, while the central mystery of why this individual rose from the depths remains unresolved.
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