"We've found a better market - an improved market."
Barratt said the controversial toothfish - caught in Antarctica's Ross Sea and considered by some environmentalists to be an unsustainable catch - as well as squid, barracuda and greenshell mussels would be sold to the new customers.
"We've made a major sale of toothfish into China."
Barratt said Sanford would gain some additional revenue through its sales of greenshell mussels to the new customers as the company was increasing its production of the farmed shellfish species.
The company expects its sales to China to increase from 8.5 per cent of total exports to around 25 per cent by 2020.
A report by Rabobank last month said rising incomes in the world's second largest economy were driving increased demand for premium seafood, both domestically sourced and imported.
Sanford posted a full-year net profit of $20.8 million last month, a 7 per cent drop on the previous year.
Shares closed at $4.34 on Friday.