That's crazy. I doubt those fish will even live in those cups that long, they're not like bettas they need disolved oxygen in the water
Maybe they have some kind of oxygen tablet or something in the water but still, it would eventually run out. There's no way that little plant provides enough oxygen for that fish. Not to mention the amount of waste in the water and stuff, eek.
This is the type of stuff that gives ignorant people the impression that fish can live in tiny enviroments and there's nothing wrong with it. No matter that the fish is probably gonna die within a few days of getting it home if it's not put in a normal cycled tank, and perhaps even if it is.