Those look to be some form of carp. They are very tough and can live a long time as long as their gills stay wet. There is a small amount of water in the bag and they are filling the bag with a gas which is probably pure oxygen. Those fish could probably live several days in that setup.

I suspect they are destined for some market where live fish are preferred and probably won't actually be in that bags that long.

In South Dakota there are some lakes that are over infested with a type of carp. There is also an ethnic group in NY City that has some kind of celebration in the middle of winter and they use a LOT of carp. They want them live so they can be slaughtered and cooked in a certain time frame and manor. Now the carp have value but what to do?

If the lakes are sufficiently frozen over, they cut fairly large holes at opposite ends. Then cut two slots out to the edge of the lake and between the holes. They stuff large nets into one hole and use heavy equipment to drag the net to the opposite hole. The catch is then just put live into refrigerated semi trailers and the loads are driven straight through to NY City and the fish are still all alive for the markets.

This was all many years ago. I have no idea if they still do it or not.