SEATTLE -- The pet food recall investigation has expanded into another human food source.

The Food and Drug Administration says Canadian fish meal makers apparently used some pet food tainted with melamine – an industrial chemical -- to make the pellets fish farms use to feed hungry salmon.

The organization is sending inspectors to check out the feed used by fish farming operations in Canada and the United States.

They have found several facilities where it was used, but say it is not necessary –at this time -- to pull farmed fish off the market.

"We do not believe that there is any significant human health risk associated with consuming these fish," said James Acheson, of the FDA.

But the FDA is sending agents to those facilities to find out what they are doing with fish that ate the meal.

The Washington State Department of Agriculture regulates those farms in this state.

State agriculture officials say they are standing by in case the FDA needs their help, but they say they don't know too much more than this: One shipment of fish food was stopped and held at the border until the FDA stepped in and let it pass.

The situation has many retailers, including the Ballad Market, avoiding farmed fish all together.

But the tainted feed may also have been used to feed hatchery fish, which are eventually released into the wild where they can be caught by sport and commercial fishers.

Just as they did when the contaminated pet food was found in hog and chicken meal, officials from the FDA say by the time it gets to your plate, the levels pose no significant risk.

Officials from the Washington Department of Fish and Wildlife say they purchased the tainted product for six state hatcheries and most was fed to fish before the problem was discovered.

It has since removed the product but some of the fish that ate it were already released into the wild.

One local salmon farm operator, American Gold Seafoods, told KING 5 its feed supplier does not use any wheat products in its meal.

The FDA now believes the poisonous chemical, melamine, ended up in the feed after it was added to wheat in China