Shellear Fish: The Climbing Fish of DR Congo

Scientific research has officially documented a remarkable biological phenomenon in the Democratic Republic of Congo: a species of fish capable of climbing vertical rock faces. The shellear, known scientifically as Parakneria thysi, has been observed ascending 50-foot waterfalls, a behavior that challenges traditional perceptions of aquatic mobility.

The discovery centers on the Luvilombo Falls on the Luvilombo River in the south of the country. According to reporting from NPR and a study published in Scientific Reports, thousands of these tiny fish migrate up the vertical wall of the falls within the splash zone. This activity typically occurs during major floods at the end of the rainy season, specifically between April and May.

Anatomical Adaptations for Climbing

The ability of the shellear to move vertically is attributed to specific anatomical traits. Researchers found that the fish utilize their pectoral fins, supported by their pelvic fins, to grip the rock. Both pairs of fins possess pads on their ventral surface that feature tiny, unicellular hook-like projections.

In addition to these hooks, the pectoral and pelvic girdles and the fin rays are well-adapted for climbing. To propel themselves upward, the fish use lateral movements of the posterior part of their body, mirroring the motion they use when swimming.

The migration is size-related, involving thousands of small- to medium-sized individuals. These fish typically measure between 37 and 48 mm in standard length, while the maximum size for the species is approximately 96 mm.

From Local Legend to Scientific Fact

While the scientific community is only now documenting this behavior, the shellear’s climbing abilities have been known anecdotally for over 50 years. In the local Sanga language, the fish is called kalumba, a name derived from a verb meaning to stick.

The path to formal documentation was long. Seventeen years prior to the April 5, 2026 report, Auguste Chocha Manda, a researcher at the Université de Lubumbashi, witnessed the fish climbing the 50-foot rockface. Although Manda filmed the event at the time, the footage was lost, leaving the observation as anecdotal evidence.

The phenomenon was later documented by Pacifique Kiwele Mutambala, a PhD student at the Université de Lubumbashi. Between 2018 and 2020, Mutambala conducted research to provide the cinematographic and photographic evidence necessary for scientific validation. This work led to the report in Scientific Reports, with Mutambala serving as one of the lead authors.

Emmanuel Vreven, an ichthyologist at the Royal Museum for Central Africa in Belgium, noted that while fish climbing has been documented in other parts of the world, it had never been recorded in Africa until this discovery.

Environmental Challenges

Despite the resilience of the shellear, the Luvilombo River faces significant anthropogenic impacts. The most critical issue is the occasional complete desiccation of the river during the dry season.

This drying is largely caused by the withdrawal of water for cropland irrigation. Such disruptions undermine the ecological continuity of the river, potentially threatening the habitat and migration patterns of species like the Parakneria thysi.

The climbing process is an arduous physical feat. Reports indicate that the fish do not ascend the 50-foot height in a single burst, but instead take numerous breaks, resting on horizontal ledges before continuing their climb, sometimes taking up to 10 hours to complete the ascent.