I see slits on each end of the tank. External overflow I'm guessing..maybe closed loop?I like tanks that are light on fish I also like tanks that don't require me to get my armpit wet if a frag falls in the back or whatever. So this is why these dimensions work well for me. I think if you're someone who wants a bunch of tangs especially the killers like sohal and clown tang in the tank then every inch you can give them will cut down on aggression especially as they age. Also i could see wanting more if it were a peninsula design considering you'd want to have a good view on either side of the rockscape