What kind of fish is swai fish?

Specifically, it's usually the Pangasius bocourti or Pangasius hypophthalmus that is marketed as "swai" in the United States.

While often called "swai," it's technically not the same as the fish known as "basa," though basa is also a type of Pangasius. The difference between swai and basa can be confusing, and sometimes the terms are used interchangeably.