i agree with you miguel, i just like to point out the extreme. in many asian countries, space is a luxury, even more so when it comes to fish keeping, hence you see the tanks with more fish than water. on the plus side, they do well in maintaining water quality at its best, resulting in the nice large fish you see.

The truth is that their water to begin with is much better in quality than the crappy tap water we have here, thus the fish are healthier and get bigger.