I watch a lot of videos of fish on YouTube, and I have noticed a theme - there are some crazy monster tanks in Asia! Like a whole bunch of of HUGE fish in a large but, not enormous, aquarium. And they often seem to look like beautiful healthy specimens despite being kept in more crowded conditions than many will advocate. Which made me wonder if anyone knows what the most common kind of filtration used in Asia on these large tanks are... It must be quite efficient! Anyone know?