KARACHI: The WWF-Pakistan on Monday warned that invasive fish species are emerging as a serious threat to Pakistan’s aquatic biodiversity and fisheries economy, following the recent identification of an alien fish at Karachi fish harbour.
On January 4, an unusual fish was brought to the fish harbour from a dhand near Sukkur. As it could not initially be identified, the fish was termed alien. It was later confirmed to be an Amazon sailfin catfish, an exotic species native to Latin America and widely kept as an aquarium fish around the world.
The Amazon sailfin catfish has a thick, armoured body covered with bony plates and is considered a highly successful invasive species. The WWF-Pakistan noted that the fish has accidentally been introduced into natural water bodies and is now spread across Sindh and Lower Punjab. Due to its widespread presence, eradication and control of the species are no longer possible.
According to the WWF-Pakistan, the Amazon sailfin catfish is among 26 invasive fish species that have been introduced into Pakistan either accidentally or deliberately. These species have become invasive and are causing serious harm to aquatic biodiversity, threatening the delicate balance and functioning of ecosystems.
Invasive fish species disrupt aquatic ecosystems by outcompeting native species for food and space, preying on them, introducing diseases, and altering habitats.
These impacts lead to biodiversity loss, economic damage to fisheries, increased water turbidity, native fish extinctions, and significant losses in commercial fishing revenue. WWF-Pakistan emphasized that the spread of invasive species poses a major threat to rivers, streams, lakes, and other natural water bodies across the country.
Historically, brown trout and rainbow trout were the first exotic fish species introduced into Pakistan, brought to Khyber Pakhtunkhwa in 1928. During the 1960s, several other exotic species including Mozambique tilapia, common carp, goldfish, and grass carp were introduced to enhance fish production and control aquatic weeds. However, all of these species later became invasive and severely affected local fish fauna.
In the 1980s, silver carp, bighead carp, Nile tilapia, and blue tilapia were introduced, while grass carp was reintroduced to boost aquaculture production. These species have since established themselves in natural ecosystems, negatively impacting native fauna and flora.
The WWF-Pakistan pointed out that although these introductions aimed to improve aquaculture, their environmental consequences were largely overlooked, and there is no disagreement that they have harmed aquatic biodiversity and natural ecosystems.
The introduction of tilapia species in the 1960s proved particularly devastating. Indigenous fish populations in warm-water regions suffered partial or complete eradication in several major water bodies. Fish production in Manchar and Keenjhar lakes declined sharply due to the rapid breeding and growth of tilapia, resulting in serious socio-economic consequences for local fishing communities.
Over the past 30 years, several catfish species including North African catfish, walking catfish, magur catfish, blunt-toothed African catfish, and channel catfish have also been introduced and are now spreading rapidly, causing severe damage to local fish populations.
The WWF-Pakistan further pointed out that, apart from deliberate introductions, species such as the Amazon sailfin catfish, guppies, and mollies have entered natural ecosystems through improper handling in the aquarium trade. These fish are creating widespread ecological damage, particularly in water bodies near cities and towns across Pakistan.
Three years ago, the WWF-Pakistan observed social media advertisements offering seeds of red-bellied pacu (Piaractus brachypomus) for farming. The organisation alerted relevant authorities against allowing the introduction of this highly invasive species. Despite this, pacu seeds are being freely imported and farmed in Sindh and Punjab.
Alarmingly, the species has already begun appearing in natural water bodies, with confirmed reports from the River Chenab near Multan and Kandhkot in Sindh. Pacu is known for rapid spread and poses a serious risk by competing for food, altering habitats, and displacing native fish species.
In response to the growing threat, the WWF-Pakistan has ensured the inclusion of invasive fish species as a potential threat in the revised National Biodiversity Strategy and Action Plan (NBSAP) under the Convention on Biological Diversity (CBD).
The organisation has urged the Ministry of Climate Change and Environmental Coordination and the Animal Quarantine Department under the Ministry of National Food Security and Research to closely monitor the introduction of exotic fish species and establish proper quarantine facilities for aquaculture and aquarium trade imports.
The WWF-Pakistan has also called on research institutions and academia to conduct detailed studies on invasive fish species, including those spreading rapidly in Pakistan such as red-belly tilapia (Coptodon zilli).
The organisation highlighted that communities living around large lakes, reservoirs, and barrages are among the worst affected, as invasive species fetch low market prices and reduce the productivity of water bodies by replacing valuable commercial fish.
Copyright Business Recorder, 2026
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