As a Standard size. They can make any size tank there customer orders.
I'm not arguing tank manufacturers make custom sizes. There are tank companies that only make custom tanks. I'm not arguing they don't exist. I have a 300g its 30" tall its a standard size 300g. It may not be a size that is sold as much as a 55g but the standard size 300 is there for anyone who wants to buy one. And a LFS can stock it as it has a dimension that will fit through any house. But they will not stock a tank that is 8x4x4 or 8x4x3 or any combination where all dimensions are over 31" cause they know it won't fit through anyones doorway.
LoL, yeah it would have nothing to do with them having to commit thousands of dollars and valuable retail space to something that doesn't sell quickly or have a high rate of turnover.
Or probably because they can't fit it through their store front door.
