aquariums with coral

[shobby]

Just wondering, why do they always say that coral needs to be seperated by several inches, but I have seen aquariums that are beautiful and they are all together. Why is that?
Shelley

 

[meowzer]

Depends on the corals....stinging corals like frogspawn will kill what it touches, and many have sweeper tentacles which can actually reach out a few inches and touch its neighbor.....now mushrooms can grow on top of each other,......only threat there is suffocation (same with zoas)