During peacetime, Gu Immortals raised Gu, their demand to purchase large quantities of mortal Gu was not high. Purchasing was a secondary option, in most cases, the primary method was the blessed land's own production. The time flow was different in blessed lands compared to the outside world, one day in the outside world was many days inside the blessed land. One year outside would mean many years in a blessed land, while each year, there would be a certain output harvested. Gu Immortals would normally not choose air bubble fish, because the price was too high, they would rather simply wait for some time.
But during wartime, when Gu Immortals frequently fought against each other, they would avoid using their Immortal Gu trump cards often, mortal Gu would be the common method of attacking, and their expenditure would be huge. Thus, air bubble fish became a sought after commodity among all Gu Immortals during the five regions war.
Sounds safe.