Tuna is a type of fish that originates from Earth. Upon embarkment to the Koprulu Sector, tuna, in some form or another, was transported with the human convicts, finding its way into cat food.
DeCandido, Keith R. A. (November 28, 2006). StarCraft: Ghost: Nova. Simon & Schuster (Pocket Star). ISBN 0-7434-7134-2