Basa, (Pangasius bocourti), AKA basa fish or swai is a species of catfish. It has become an important farm raised food fish. Basa fish is farmed mainly in its native Indochina, especially the Mekong delta in Vietnam.
Concerns over contamination from the water used to farm basa has led to it being banned in three US states (Louisiana, Mississippi and Alabama). Substances which have been banned in US, including antibiotics, have been found in samples of basa from Vietnam. It should be noted that all three of the states mentioned above (plus Arkansas) are also significant producers of farm raised catfish. Although basa is in the catfish family, it may no longer be legally referred to as "catfish" for marketing purposes in the United States. In 2000, the Catfish Farmers of America "secured the introduction of a bill in the U.S. Congress stating that only channel catfish (Ictalurus punctatus), a native North American catfish, could be called “catfish” for marketing purposes in the United States." (source "Catfish Farming in Mississippi")