Recently my husband and I dined at a somewhat high-end restaurant and had an ahi tuna steak for an entree. My husband didn't like it, only had half of it, and we brought the leftovers home. My husband now suspects it wasn't ahi tuna but some other fish. I'm wondering, is there any way for us to have that piece of fish tested? Or is that a crazy-expensive ordeal that's just not worth it? I'm not really hung up on this, but I am curious. It would be nice to prove whether the restaurant mis-labeled the fish or not.
'Was your grouper sandwich from a restaurant really grouper?' is pretty much a stock investigative news report when Florida television stations run out of other ideas for that segment. Not sure who their usually testing company is, but if not fishdnaid.com, it's probably quite similar.
And if they tell you it was a Bigeye and not a Yellowfin will that assuage your fears?
Chances are it sat in the sun a bit too long and had elevated histamine levels-that's the most common problem-with pelagics-any reputable restaurant would have taken it back and struck it off the bill.
I recently used www.fishdnaid.com to test samples of fish fillets (mostly grouper and sea bass) I had obtained from a number of local raw fish vendors, including Whole Foods. I mailed unlabeled pea-sized samples of the fish to the company and received reports a few days later. (The lab analyses confirmed that all of the fish had been accurately labeled by the vendors.)
I found fishdnaid by searching the web for the name of the scientist who runs the company, David Price, who had been quoted in articles discussing fish fraud that I had seen, and who had been selected by the state attorney general's office for a widely-publicized fish id analysis a few years ago.
The lab accepts raw or cooked fish.
(From the address I sent the samples to, I got the sense that he might be running this company from his home rather than from a university lab, but the results were really all that mattered.)
There are also other companies that offer a similar service -- try searching the web.
Or you could try searching for newsmedia articles on the topic, then contacting scientists who are mentioned in the articles and asking them if they perform the service.
There are many places that do DNA testing of fish. But I don't know if the testing works on cooked fish.
A LOT of fish sold commercially is mislabeled. Look at http://phe.rockefeller.edu/barcode/blog/2007/03/24/routine-dna-testing-in-fish-industry-to-help-people-and-fish/ where they discuss studies where the MAJORITY of red snapper and grouper from various restaurants and vendors were in fact something else.
One example of a company that does DNA testing of fish: http://www.fishdnaid.com/