This is the moment thousands of blackchin tilapia were seen invading a waterway in Bangkok.

The invasive fish have rapidly increased, consuming smaller fish and roe, posing a significant threat to fish farmers in Thailand.

Footage shows them on the outskirts of the city in Samut Sakhon.

They were reportedly discovered in Makkasan swamp, connected to the Chao Phraya River, constituting 20 per cent of the dead fish stranded when the 72,000-square-meter swamp was drained in preparation for wet season flooding.

The Department of Fisheries has implemented measures to address the situation, including controlling the blackchin tilapia population in aquatic habitats, releasing predator fish such as barramundi into the wild, and utilizing removed blackchin tilapia, among other strategies.

The Bangkok Metropolitan Administration (BMA) announced cooperation with the Department of Fisheries to curb the fish population on July 13.

Prime Minister Srettha Thavisin approved a Ministry of Agriculture and Cooperatives measure to purchase blackchin tilapia at 15 baht (approximately 0.32 GBP) per kilogram for use in fertilizer production, funded by the Rubber Replanting Aid Fund.

This initiative aims to incentivize local fishermen and the public to help in catching the fish.

Bangkok governor Chadchart Sittipunt noted that the blackchin tilapia had spread from Samut Songkhram to other areas over time, with their numbers increasing in Bangkok's Bang Khunthian, Thung Kru, and Bang Bon districts, affecting roughly 900 aquaculture farmers.

DNA tests confirmed that blackchin tilapia found in waters across 13 provinces originated from the same parent stock.