How many guppies do they raise here? This many:
There were nearly as many ponds devoted to other livebearers: platys, swordtails, mollys. In the case of the swordtails a single giant pond was subdivided with hanging nets. I’m not sure what the difference is between the different pond arrangements.
These are also all fish that I think of as needing the exact opposite water (hard, alkaline) as tetras, but as best I can tell they don’t mess with the water chemistry for anything but discus.
Discus must not yield to mass-production techniques, because the discus tanks looked just like discus tanks everywhere.