A WCNC hidden camera investigation reveals there's something fishy when it comes to ordering certain seafoods at some Carolina restaurants.

Customers are not getting what they're paying for; they're getting cheaper substitutions. Investigative reporter Stuart Watson looked at grouper on Monday night and now we order the red snapper, but what did we get?

Red snapper is becoming scarcer and more expensive and we found some seafood restaurants are substituting cheaper fish instead.

We took hidden cameras to five Carolina seafood purveyors and ordered the red snapper.

Tests showed two of the five so-called red snappers were actually tilapia.

Dr. Mahmood Shivji says, “Tilapia is actually a good tasting fish, however it's not a snapper or a grouper.”

Splash in Cornelius got it exactly right. Blue Bay Seafood in Salisbury served a cousin of the red snapper, the crimson snapper. The Overseas Fish Market on South Boulevard in Charlotte sold us a vermillion snapper.

“I would think the average consumer would probably not be able to tell because they don't eat seafood that often,” said Dr. Shivji.

Two restaurants made very clear substitutions. We ordered the crusted red snapper and the shiromi red snapper sushi at Nikko Japanese Restaurant on South Boulevard. In both cases our lab tests found the fish was really the cheaper tilapia. Owner Joanna Nix tried to brush it off as a simple problem of translation. ,p> The menu doesn't read "white fish." It reads crusted red snapper, not in Japanese, in English.

“This is just English difference,” said Nix. Reporter Stuart Watson explained to Nix that’s it’s a different fish and there’s a big price difference.

Watson said, “Tilapia is a cheaper fish. So if people think they're getting red snapper.”

Nix replied, “Oh you're coming from it that way.”

Well, yes, we're “coming at it that way” -- that consumers should get what's advertised.

Dr. Shivji said “One would assume the motivation the restaurants are buying a lower priced fish, mislabeling it and selling it for a much higher price.”

At Joel's Gourmet Sushi near Lake Norman in Mooresville, we ordered the red snapper nirvana roll. The lab determined the fish is tilapia

“Yeah it is tilapia,” said Owner Joel Jose. He added “I'll change that on our menu. You're right. Thank you for pointing that out.”

Joel’s Gourmet Sushi may be thanking us for pointing out what he regards as a menu error, but the North Carolina Department of Agriculture regards such mislabeling as a violation of state and federal law. When we asked the head of the Food and Drug Division about the fish swap, he wanted to know names of the restaurants and he wants to know the names of their suppliers.