I watched the show with the beer keg tank too. And the original design was the size of a Keg. Wayde decided that it was way to small, so they made a mold from a larger wine barrel and the tank ended up approx. 89g. Which is a good size for a lot of (not all) African Cichlids.
A Short long tank is best for African Cichlids, but fish are adaptable. Not that they should have to be, but they can. Also inside the ugly fake coral were a bunch of holes going through it that could be used for hiding, similar to a rock wall.
There are people that have all male Malawi tanks. It's done in order to not have to deal with the enormous amount of fry that African Cichlids produce. You can read the article below to find out the how to's and why's of it all.
All-Male Malawi Tank
The Kegger fish tank isn't the ideal or natural tank that would be preferable, but that's not what the show is about. It's about the unique, one of a kind tanks to fit any human's requirements.
How well any of the fish do in these elaborate & unique tanks we'll never know, unless we build a few of our own as an experiment. Which would be a bit to costly.
And they may only have that many fish in the tank for the show, we don't now. After the filming is done they may remove some for the health of the fish. A tank that is really full of beautiful, bright colored fish films better than a few fish that immediately go into hiding.
There is so much that we don't see that goes on. All we saw was them filling the tank up with water from a garden hose, no de-chlorinater or water conditioner of any kind. No heating of the water, basic stuff we all know they have to do or all the fish will be dead within 48 hrs.
The people buying these elaborate tank don't know anything about fish but the tank builders do. And if you watch them at the fish warehouses when they are buying fish, it obvious that they really love fish and know a lot about them. But they still have do do what looks good for the camera first. Then when the cameras are gone, I'm sure they put things right for the fish.
If they were killing the fish they never would have been able to build up the kind of business they have.