Tanks
There are probably three aspects that you will need to consider in purchasing your tank. Before considering these, you should bear in mind what the purpose of the tank is. Sounds simple, but lose sight of it and you'll end up with something that isn't fit for purpose. That said, the first aspect that you should consider is size. In the case of aquarium fish tanks, size really does matter. Go for the largest that you can comfortably afford and that you have room for. Probably the smallest would be 24" x 12" x 12" or 60cm x 30cm x 30cm. Remember the weight! Even this will contain almost 55 litres or 12 gals (14 US gals) and weigh c. 55Kg or 120lbs.
What shape will you go for? A rectangular shape is traditional, but you could have any shape that you so desire. However, do consider that the tank's surface area has a bearing upon the exchange of gases (CO2 and O2). The larger the surface area, the less assistance you will need to give your tank in keeping oxygen and carbon dioxide at healthy levels.
Traditionally, tanks were made of glass. It is transparent, flawless, durable and strong. Of course it is also inflexible - the sides of your tank will have to be straight. This needn't restrict it to only being rectangular in plan. Far from it, but you do have to consider that each side will need to be joined to its neighbour. Therefore you will have seams and they will break up the view, no doubt. So what about acrylic? It's flexible - a single piece can be moulded, but then may well become distorted and it does scratch more easily than glass.
Just to finish on a couple of points with regard to the location of your tank. Don't place it in direct sunlight or any other heat source. Also, bear in mind that you will need power to enable the use of pumping, filtration, lighting and heating.
