First it was cats and dogs, then hens and hogs that were actually in the human food chain. Now it's fish.

The United States Food and Drug Administration stated that it doesn't believe humans are at risk from eating pork or fowl products, at least insofar as the toxin melamine - a byproduct of the coal production industry - is concerned. Now melamine, which had been detected in raw materials for the pet-food and other food industries from China, has been found in the feed for farmed fish.

In a twist, the fish feed was made in Canada. But like the contaminated pet food, it contained wheat gluten imported from China, which had been spiked with melamine.

Why would anybody add melamine to feed? To create the impression of a higher protein content than the material actually contains. Under superficial chemical analysis, melamine and protein give the same nitrogen-rich readings.

The level of contamination is expected to be too low to pose any danger to human health, said Dr. David Acheson, the FDA's assistant commissioner for food protection, not that he or anybody knows whether the farmed fish in question have actually been eaten. He also admitted that the FDA doesn't know how the long-term ingestion of melamine may affect the health.

The tolerance ratio for melamine in the food chain is zero.

The FDA has kept the information close to its chest, not revealing which fish are involved, let alone how many.

Last week it said that 400 pigs and 2.7 million chickens that ate melamine-tainted foods had been eaten by Americans. The animals ate feed that contained salvaged pet food used to manufacture their feed.
 
The melamine scandal began on March 16, when the Canadian company Menu Foods recalled more than 60 million containers of dry pet food, made under almost 100 different labels and brands, some of them very expensive. Menu Foods subsequently expanded its recall five times as the toxin was detected in more and more brands, and was joined by about a dozen other petfood makers.

Officially 16 cats and a dog suffered fatal kidney failure because of the melamine-tainted food - cats have notoriously sensitive renal systems. But unofficial reports put the toll in the thousands.

CNN reports today that the Chinese authorities have arrested the manager of the Chinese company suspected of selling the contaminated wheat flour to American manufacturers. In fact, they arrested Tian Feng of Binzhou Futian Biology Technology two weeks ago, the news organization reports, adding that Feng denies any wrong-doing and says he doesn't even know what melamine is.

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