A third of tested restaurant lobster dishes actually contain cheaper fish meat, investigation shows

Restaurants serve lobster in rolls, soup, ravioli and even on pizza – and diners are willing to pay a premium for the delicacy.

But an INSIDE EDITION investigation, which will air in full on Monday, has found that you might not always be getting the real deal.

INSIDE EDITION visited 28 restaurants around the county, including local seafood spots and national chains. Nathan's, Red Lobster and even the Soupman – the New York eatery made famous by Seinfeld – were among them.

READ MORE: 'Freaky Fast' Delivery Guys Drive at Dangerous Speeds, Make Illegal Turns to Drop Off Food on Time

The meat was scooped out from a variety of lobster dishes and sent off to a lab, where DNA tests were carried out to see if there was anything fishy about the lobster.

See photos related to the story:

It emerged that in 35 percent of the samples, the lab found cheap substitutes instead of lobster.

A restaurant called 'Get Hooked,' just outside of Tampa, Florida, served up lobster rolls – but INSIDE EDITION found samples of the meat actually contained whiting, an inexpensive fish.

The owner told IE he did, "not purposely rip off the public."

The restaurant owner says he makes his lobster rolls with a frozen mixture. It has some lobster, but he acknowledges it's filled with other, cheaper fish like whiting and pollock.

And it wasn't just local restaurants. At the country's largest seafood chain, Red Lobster, INSIDE EDITION ordered lobster bisque soup from three different locations and scooped out the meat.

One sample included only langostino, a less expensive meat more closely related to hermit crab than lobster, and two others had a combination of langostino and lobster. The FDA told INSIDE EDITION that soup with only langostino cannot be called lobster bisque. It must be labelled as langostingo lobster bisque.

In a statement, Red Lobster said: "Our Lobster Bisque can contain meat from Maine lobster, langostino lobster, or, in some cases, a combination of both. Both types provide the bisque with a rich, sweet taste that our guests love."

READ MORE: Instead of White Tuna, Some Sushi Restaurants Secretly Save Cheap Fish That May Cause Sickness

But there was some good news. Some samples, such as the lobster bisque from the Soupman, came back loaded with lobster.

Celebrity chef and best-selling author Rocco DiSpirito says there should be no compromise when it comes to lobster rolls.

They should be "all lobster, not a mixture of lobster and whiting and any other kind of fish," he said. "The whiting, pollock thing is not what you'd expect when you order a lobster roll."

For more on the investigation, tune in to INSIDE EDITION on Monday.

More on AOL.com:
Grandmother uses staple gun to fight off attacker
White House seeks $1.8B in emergency funds for Zika virus
Colonial Williamsburg criticized for 9/11 image in Super Bowl ad