As long as it is 2 feet deep from front to back and at least 20 inches tall. This gives enough room for corals and rock with some open area in the front and provides a better visual experience IMO. I got a new tank last year and finally got what I wanted in this area. Mine is five feet wide but four or even three feet wide would have been okay I think as long as I had the depth from front to back. I got a Custom Aquariums tank and have been happy with it and would get another. It is 5'X2'X2'.