Some fish imported to Hawaii is treated with carbon monoxide to keep it from turning brown.

It's not dangerous but it does disguise the age of the fish. Many countries don't allow the use of carbon monoxide on fish, but the U.S. Food and Drug Administration does if it's on the label.

Carroll Cox said it isn't always at Don Quijote.

"It's just deceptive and the concern is that there are health risks associated with this. There have been actual people getting sick. It masks the lack of cleanliness, the unsanitary condition, and I as a consumer wanna know that and then I would be reluctant to purchase that," said Cox.

Cox has filed a lawsuit against Don Quijote store. The suit charges the store with mislabeling and false advertising. Managers at the store had no comment.

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