Farmed fish in the U.S. have been fed Canadian-made meal spiked with an industrial chemical linked to the ongoing pet food recall, officials said Tuesday.
However, U.S. health officials said the level of contamination was too low to pose a risk to humans.
The Canadian-made meal included what was believed to be wheat gluten, imported from China, contaminated by the chemical melamine and related compounds.
Pigs and chicken have also been given the contaminated feed.
It wasn't immediately clear if any of the farmed fish has entered the food supply yet.
However, Dr. David Acheson, the FDA's assistant commissioner for food protection, said at least some of the farmed fish were still too young and small to be sold.
Meanwhile, investigators were visiting other U.S. aquaculture farms that fed their fish with the tainted meal.
Acheson said fish samples would be screened for signs of melamine.
"Depending upon what we find in that testing, that is going to drive the next steps," Acheson told reporters.
Federal health inspectors in the U.S. have already cautioned that they expect to find more farms where hogs and poultry have consumed the tainted product.
Investigators are still trying to get a grasp on how far the melamine-contaminated pet food crept into the animal feed system.
Officials at the Canadian Food Inspection Agency have said the agency was keeping a close eye on the U.S. situation, but had no reason to believe there was any risk in Canada.
A CFIA official told CTV.ca the slaughtered hogs and chickens were believed to have been distributed within the U.S. only.
However, the official pointed out that the probe of the affected poultry is still underway, and there is a slight chance the investigation will be widened to Canada.
