MR ONG Kim Pit's decision to become a fish farmer in 1990 was made out of necessity, rather than choice.
Back then, the farmer, now 65, had been rearing pigs in Punggol for about 30 years. But the Government's decision to phase out pig farms in the early 1980s saw him turn to fish.
Armed with only the know-how of pig farming, he started out rearing freshwater fish such as marble goby and barramundi in a Lim Chu Kang pond.
But after three years, when the rent proved too expensive, he bought a fish pen off the Lim Chu Kang coast to farm saltwater fish, starting with twenty small nets and 3,000 barramundi.
The transition from pigs to fish was not a smooth one. "If a pig falls sick, you inject it with medicine. But fish are trickier," he said. "Species such as grouper will definitely come down with an illness at some point. Their throats and mouths may rot."
And there was competition from other fish farms. The Jurong Fishery Port has since stepped in to regulate prices. "In the past, I would sell a kilogram of fish for $5, and they would sell it for $4.50," said Mr Ong.
But he has no regrets making the switch, even if he lost as much as 3,000kg of fish in the beginning. "As farmers, we need to have confidence in ourselves," he said, adding that he would constantly analyse where he had gone wrong to find ways to improve.
After losing $70,000 in barramundi because of diseases, for example, he turned to milkfish and mullet. It paid off, with these two species less prone to illness. Their feed, of stale bread and uncooked instant noodles, is also cheaper.
Now a seasoned fish farmer, he even uses high-tech machinery, such as a pump to improve oxygen levels in the water.
His farm rears at least 400,000 fish today, most of them bound for wet markets and supermarkets here. He earns $2,000 to $3,000 a month, depending on orders from Jurong Fishery Port.
But Mr Ong intends to call it a day after two more years. His three sons are not keen to take over the business.
"It's not an easy job to follow," said his second son Jun Yuan, 30. "The operation and maintenance costs will be too high for me to carry on for another decade."