Yup, any clean source of O2 will do. We prepare fish for shipment by first moving them to a clean tank and fasting them for 24-48 hours to purge their guts. Fish pooh in the bags will spoil the water and deplete the O2 real fast. 1/3 water + 2/3 O2 in the bag is s.o.p. Depending on how much fish are in what size bag, they can stay alive up to 48 hours.

Nice pics, badflash. Btw, the tilapia cultured here are mostly composites of various O. nilotica strains. Basic foundation is from the 8th generation of the GIFT ( Genetically Improved Farmed Tilapia) line developed in the 1980's by a multi-national project to improve tilapia.