Thousands of fish have died in coastal farms off Changi, in a repeat of last year's nightmare for farmers.
Farmers woke up yesterday morning to the sight of their fish floating belly up - the mass deaths had occurred through the night, so they had no opportunity to try to save their fish.
Dead fish were also seen along the Pasir Ris shoreline.
The Agri-Food and Veterinary Authority of Singapore (AVA) attributed the deaths to gill damage caused by plankton. Lab tests conducted so far did not detect biological toxins in the fish, and fish from local farms remains safe to eat, an AVA spokesman said.
At around the same period last year, 160 tonnes of fish died suddenly, also after being poisoned by plankton, and the 39 affected fish farms lost hundreds of thousands of dollars..
Yesterday, some despairing farmers told The Sunday Times that they hope to get more support and training in modern farming methods that can minimise pollution and bacteria growth, particularly since the authorities are encouraging the trade to help boost Singapore's self-sufficiency in food production.
AVA had advised farmers to take precautions since Feb 16, when there were elevated plankton levels detected in the East Johor Strait.
But the overnight deaths took most by surprise.
"I thought I was prepared this year. I even had aerated tanks to save the fish if a few started dying," said fish farmer Timothy Hromatka, 42, who studied marine biology.
"But it was too late," said Mr Hromatka, who lost most of his fish.
Fish farmer Phillip Lim, 53, noting that a few fish had started dying as early as mid-February, added dejectedly: "That was just the 'appetiser'. Friday night was the 'main course'."
The former president of the Singapore Marine Aquaculture Cooperative estimates that almost 50 farms were affected this time round.
"It could be worse than last year. This year, it looks like more fish died and the wild fish also died," added Mr Lim, who estimates his losses at more than $50,000. He reared popular species such as seabass, snapper and pomfret.
Fish farmer Daniel Wee, 40 is in the same predicament.
He had received tens of thousands of dollars from the AVA to kick-start his fish farm again after last year's mass deaths wiped out his stock, and spent another $20,000 on fish feed. But yet again, most of his 70,000 fish were wiped out. "It's a really, really tough business now," said Mr Wee, who estimates he lost $100,000.
"We need to learn new methods to take local fish farming to the next level."