If you've ever eaten farmed fish, you may not want to know the answer to the question posed in the headline above, based on previous reports I've posted about wild baby salmon being contaminated with sea lice. An international group of bird conservationists believes the practice of fish farms using chicken feces for food -- routine in Asia -- may be responsible for the spread of the avian flu.
According to this excellent piece in The Independent (free text link below), using chicken feces is common in integrated livestock-fish farming, which also involves the transfer of pig and duck waste directly to fish farms.
Even worse, some believe the United Nations' Food and Agriculture Organization -- that oversees this practice -- may have been aware for some time, there were serious health risks involved with mixing farmed fish and animal feces.
Without exposure to such toxins -- don't forget mercury -- fish would be nearly a perfect food. If you want to get same nutritional benefits, but without the dangers, I recommend taking a high quality fish or cod liver oil daily.
The Independent December 28, 2005