fish breeding tanks

I can't believe that this webmaster didn't know about something like this. They are everywhere now in Laos. They're for raising fish or fish breeding. Each section had net or screen to keep fish in there. The water level and water quality is the same as the river. All they have to do is throw in whatever they use to that compartment to feed the fish.
Remember that if something wrong with water in the river (ex. low oxygen..etc), it will affect the fish they raise too)

The tanks or (55gal. empty barrels)  are used as floating devices, to keep the  whole section floating relative to the river's water level.