‘Pitch-black’ blackchin tilapia severely damaging shrimp farms

A shrimp farmer in Samut Songkhram has decried the devastating impact of the invasive blackchin tilapia after discovering tonnes of the fish in her ponds instead of the shrimp that once provided a stable income for her family.

Mrs Amornwan, 61, who operates more than 50 rai of shrimp ponds in Village 5 of Yi San subdistrict, said she was confronted with a painful reality during her harvest time at the end of her most recent cultivation cycle. Rather than finding marketable shrimp, she discovered more than 5,000 kilogrammes (five tonnes) of blackchin tilapia.

The fish were sold for only 8 baht per kilogramme, generating just 40,000 baht in revenue — far below the cost of shrimp seed stock, feed and labour invested throughout the farming cycle.

She said the problem had grown beyond the capacity of individual farmers to manage, adding that even large-scale aquaculture operators were struggling with the infestation.

“This is a major issue that small farmers cannot solve on their own. Even larger farms are facing the same difficulties,” she said. “Fortunately, I do not have any debts. If I had borrowed money to invest like many other farmers, I might not have been able to continue in this profession.”

The crisis is also affecting the wider local economy, according to Netchanok, 40, a major blackchin tilapia trader known locally as “Sia Nui Pla Sing”.

She said the invasive species was causing severe damage not only to aquaculture ponds but also to the livelihoods of farming communities.

“Farmers release juvenile shrimp, crabs and fish, but many never reach maturity because blackchin tilapia consume them while they are still small,” she said.

“The resulting losses are enormous, while the market price of blackchin tilapia remains extremely low because consumers generally do not favour eating them.”

Feed and bait

Mrs Netchanok explained that fish traders currently purchase blackchin tilapia directly from ponds for just 5 to 6 baht per kilogramme before reselling them for 6 to 7 baht per kilogramme. Most are used as animal feed or fishing bait, including for sea bass, catfish and mud crab farming, or frozen for use in blue swimming crab traps.

“The problem is that there are very few buyers and prices are extremely low,” she said.

“Many farmers have to hire workers to remove the fish, spending tens of thousands of baht, yet sometimes earn only 4,000 to 5,000 baht from sales. They are effectively operating at a loss before they even begin to recover.”

She called on government agencies to take urgent and meaningful action to address the crisis, including introducing price support measures, organising campaigns to remove blackchin tilapia from canals and waterways, and providing shrimp, crab and other commercially valuable aquatic stock to help farmers rebuild their livelihoods.

Origins in Africa

Blackchin tilapia is an African species that was originally imported to Thailand for research purposes in 2010.

The importer, the agribusiness group CP Foods (CPF), said the fish at its facility in Samut Songkhram died within three weeks and were disposed of using approved methods, with samples sent to the Fisheries Department.

However, blackchin tilapia later started showing up in local waterways, with the first reports in 2012. As their population grew, native fish species started decreasing in number, leading to a major eradication campaign in 2024.

CPF has denied any link between its activities and subsequent discoveries made across the country, and filed a libel suit against one of its most vocal critics.

Meanwhile, a new study by researchers from Chulalongkorn University has concluded that blackchin tilapia were introduced to Thailand at multiple places and in multiple ways, and not as a result of a single introduction as believed earlier.