The Fish pack is based on the orginal Chouinard Equipment Fish pack. Introduced sometime in the early 70's. Thanks to Dane at coldthistle.blogspot.com for lending me his pack to work from. As you can see Dane's pack is heavily modified from the original.
available in 12 0z orange cordura to match the color of the original or 16 oz Ballistic nylon ,in Red or Royal Blue, to match original fabric. I cannot find a source for orange ballistic nylon.