Ocean Fresh Seafoods owner Chris Russell said sales at his Fyshwick markets store would be about 10 times those of an average week.

"It's definitely the second-biggest week after Christmas, and Thursday is the big day everybody buys seafood for Good Friday," he said.

"From previous years and what I'm forecasting, there's a big call for people buying fresh tiger prawns and freshly cooked oysters."

Mr Russell, planning for his busiest Easter since he bought the business in 2012, said the split would be about even between fresh fish and the crustaceans - prawns, oysters and lobsters.

Fish and chips from the store's cafe were again expected to be popular on Thursday and Friday .

Mr Russell said the store would have more than 1000 kilograms of salmon available, up from 200-300 kilograms in an average week.

"I'd expect upwards of four tonnes of cooked tiger prawns, and over 1000 dozen of oysters, up from 150-200 dozen in a normal week," he said.

Across the road, FishCo Down Under owner John Fragopoulos said a "bumper late prawn season" meant suppliers from northern NSW and Queensland were still harvesting fresh prawns ready for shoppers next week, and prices would be cheaper than usual.

He said there would be eight tonnes of tiger prawns arriving across Monday and Wednesday, and four tonnes of cooked King prawns.

"Because there's more fresh [this year] and cheaper, I hope people will buy more," Mr Fragopoulos said.

"Our motto is always 'try before you buy', even oysters."

The veteran business owner said weather conditions in Queensland meant some possible limitations on fish availability for his store.

"Whoever wants a particular fish, put an order through and make a call early," he said.

Fish and seafood wholesaling contribute more than $4 billion to the Australian economy annually.