Five Star Fish managing director Danny Burton resigned last week, just two days after Boparan announced he had secured the backing of the majority of Northern Foods' shareholders, paving the way for his takeover.
The news that Burton had resigned so soon after the announcement sparked industry rumours that Boparan was preparing to exit the fish category by selling Five Star Fish possibly to help fund the acquisition of Northern Foods and concentrate on his existing poultry supply operation 2 Sisters Food Group.
But a spokeswoman this week denied "categorically" that Five Star Fish was up for sale.
"It is a key part of 2 Sisters Food Group's strategy for growth in the protein sector," she said.
Burton had been at the helm of Five Star Fish a leading supplier of fish to the foodservice industry since 1999.
He retained his position after Five Star Fish was bought by Boparan last April, following the collapse of its previous owner British Seafood Group. At the time, Boparan was hailed for his role in saving 332 jobs at Five Star Fish, which is thought to have an annual turnover of circa £65m. The spokeswoman said Five Star Fish would be led by 2 Sisters MD Eddie Power from now on.
2 Sisters Food Group said it respected Burton's decision to spend more time with his family and "pursue personal interests".
"Danny is highly regarded by all who have worked with him at Five Star Fish over the years for his integrity, passion and drive," the spokeswoman added.
Aside from Five Star Fish, Boparan's fish and seafood interests include FishWorks a high-end London fishmonger and restaurant chain as well as the Harry Ramsden's chain of fish and chip shops.