The company, at the head of Loch Fyne in Argyll, Scotland, began as a modest operation in 1978 when local landowner Johnny Noble and marine biologist Andy Lane registered their business farming oysters in the waters of the loch and selling them from a shed beside the A83.
Today Loch Fyne sells 2.5 million oysters a year, as well as 400 tonnes of mussels and nearly 1,000 tonnes of smoked salmon.
Its seafood is exported all over the world and is on the menus of first class airline cabins, luxury hotels and Formula One racing events.
Admission to the event on Saturday and Sunday costs just £5 and is free for children.
This includes chef demonstrations, face painting, oyster shucking displays, a magician, art and craft stalls and live
Children also get free entry to the ceilidh and spectacular fireworks display over the Loch on Friday night. For adults it'll be £10 each.
Food is available from two hot food stalls or, alternatively, a seafood meal plus a glass of fizz on arrival and entry for the ceilidh cost just £40 for two adults.
Festival goers can get a behind-the-scenes tour of the oyster farm (Sat and Sun £5/£2) or have a tour of historic Ardkinglas House on Sunday with champagne and oysters for just £20.
Tours and tasting of Fyne Ales is available for £10.
Tickets have almost sold out for an acoustic set by Scottish band Hue and Cry, famous for hit singles such as “Labour of Love” and “Looking for Linda”, and still going strong.
An audience of just 140 will also enjoy a magnificent seafood buffet at the event on Saturday 12th May.
Tickets are available via Eventbrite.
“We are planning a showstopper of a weekend,” said managing director Cameron Brown.
“Loch Fyne is a global success story and we want the public to come and help us celebrate forty fantastic years.
"We are excited about giving visitors a sneak peek at what goes on behind the scenes of our oyster farm, and I’m looking forward to having a bop at the ceilidh, and hearing Hue and Cry’s iconic Scottish Hits.
"History lovers will have a chance to look around Ardkinglas House on our founder’s estate whilst enjoying champagne and seafood, and nature lovers will be given special insight into the natural environment and abundant wildlife around our location on the shores of Loch Fyne.
"There is truly something for everyone at our ‘Fyne at Forty’ weekend.”