Aquariums: I just saw this in a fish shop. Is it a good setup for a low-cost marine aquarium with only clownfish and little else?

I asked the owner if the tank size was adequate or if it was simply for display.

He said yes, they don't need much more, that they're clownfish already raised in aquariums and are very hardy. I'd be tempted to get a similar marine tank, but first I want to know if they would really thrive in these conditions with an anemone.