i guess for me is that i like large monster fish that's between 2-3 ft long... since i already have about 20 of them (average 1ft right now)... i want them to have a home in my home.. not a prison.. so the biggest tank that i can provide is a must to ATTEMPT to provide that kind of environment... currently have a 225g, planning on having a 550g... that's the biggest i can provide without sacrificing too much space or other things.. anything bigger would be too big for 1 person to upkeep.,., especially when i have more important things to deal with like job, family, kids, bills, and other hobbies..., this is just part of my life which defines "me"... on another note, this is a hella expensive hobby and can easily be turned into obsession since there are plenty of species out there (and more new ones) that at one point we all want to keep at the same time.. hehehe