The World Wide Fund for Nature (WWF-Pakistan) has warned that invasive fish species are becoming a major threat to Pakistan’s aquatic biodiversity and fisheries-based livelihoods, following the recent discovery of an alien fish at Karachi Fish Harbour.
According to the organisation, an unusual fish was brought to the harbour on January 4 from a dhand near Sukkur. As it could not be identified initially, it was labelled an alien species. Experts later confirmed it to be the Amazon sailfin catfish, an exotic fish native to Latin America and commonly kept in aquariums worldwide.
WWF-Pakistan explained that the Amazon sailfin catfish has a heavily armoured body and is among the world’s most successful invasive species. The fish has unintentionally spread into natural water bodies and is now widely present across Sindh and parts of Lower Punjab. Due to its extensive spread, its control or eradication is no longer feasible.
The organisation noted that this species is one of at least 26 invasive fish introduced into Pakistan over time, either deliberately or accidentally. These species disrupt ecosystems by competing with native fish for food and habitat, spreading disease, preying on local species, and altering aquatic environments. Such impacts result in biodiversity loss, declining fish stocks, increased water turbidity, and economic losses for fishing communities.
WWF-Pakistan highlighted that Pakistan’s history of introducing exotic fish began in 1928, with trout brought to Khyber Pakhtunkhwa. Later introductions, including tilapia and various carp species, were meant to boost aquaculture but eventually harmed native fish populations. Tilapia, in particular, caused severe declines in indigenous species in major lakes such as Manchar and Keenjhar.
In recent decades, invasive catfish and aquarium species have further worsened the situation. WWF-Pakistan has urged strict monitoring, quarantine measures, and scientific research to prevent further ecological damage and protect the country’s aquatic ecosystems
