The recent revelation of Pterygoplichthys disjunctivus, an Amazonian armored catfish, in Nepal’s Lohandra River has stirred profound concern among researchers and conservationists. This unprecedented discovery, detailed in a study published in BioInvasions Records, marks the first documented occurrence of this species in Nepali rivers. Named for its distinctive vermiculated scales and known colloquially as the janitor fish due to its role in aquariums, P. disjunctivus poses an existential threat to Nepal’s freshwater ecosystems.
Initially identified during extensive surveys from May 2019 to July 2023, forty-three specimens of P. disjunctivus were found inhabiting the Lohandra River, located in eastern Nepal. Asmit Subba, a co-author of the study and zoologist at Tribhuvan University, emphasized the challenge of determining the fish’s origin, suggesting potential routes from South Asia or through the aquarium trade. Their adaptability, including the ability to survive out of water for extended periods by absorbing oxygen through their intestines, enhances their invasive potential.
While P. disjunctivus is native to the murky waters of the Amazon, its introduction into Nepal's rivers lacks a clear narrative. Hari Sharma, an associate professor at Tribhuvan University, raised concerns over the species' impact, noting similar disruptions observed in neighboring Indian states bordering Nepal. Reports from these regions indicate declines in native fish populations, attributed to the competitive advantage of these invasive catfish.
Research methodologies involved meticulous documentation and analysis, confirming the species' identity through detailed physical examinations and comparison with known taxa. Despite efforts to restrict their presence to the Lohandra River, questions remain regarding their potential spread to other river systems in Nepal. The interconnected nature of Nepal's river network suggests a plausible scenario of upstream migration from neighboring regions.
The implications of this invasion extend beyond ecological disruption. Genuine Prajapati, an aquatic biologist, highlighted the absence of natural predators for P. disjunctivus in Nepal, posing a critical challenge to the country’s aquatic biodiversity. Concerns are compounded by existing stresses on Nepal’s rivers, exacerbated by climate change and inadequate regulatory frameworks for aquarium trade waste disposal.
Addressing the threat posed by P. disjunctivus demands immediate action. Urgent measures include raising awareness among local communities and enforcing regulations on the release of exotic species into natural water bodies. The absence of stringent controls on aquarium trade and aquatic imports further exacerbates the risk of invasive species proliferation. Long-term strategies must encompass comprehensive monitoring, regulatory reforms, and adaptive management to safeguard Nepal’s freshwater ecosystems.
In conclusion, the discovery of P. disjunctivus in Nepal underscores the urgent need for proactive conservation measures. As efforts intensify to mitigate the impacts of invasive species, collaborative research and policy interventions will play pivotal roles in protecting Nepal’s aquatic heritage from irreversible ecological harm.
