The tank is the one decision you cannot cheaply undo, so it is worth a few minutes of thought before you buy.
Footprint beats gallons
Two tanks of the same volume can be completely different homes. A long, shallow tank gives fish room to swim horizontally, gives you a wider aquascape, and puts the surface within easy reach for fish that breathe air. A tall, narrow tank of the same gallonage gives you less usable swimming space, less light reaching the substrate, and a harder tank to plant. For almost every freshwater setup, longer and wider wins.
Bigger is genuinely easier
This is counter-intuitive to beginners and it is the single most useful thing we tell them. A larger volume of water dilutes waste and resists temperature swings, so mistakes happen slowly enough to catch. The same missed water change that is a crisis in two gallons is unremarkable in twenty. If you are choosing between two sizes and can house and afford the larger one, take it.
Rimless, braced, and what that means for you
Rimless low-iron tanks are what aquascapers use — no plastic trim, far clearer glass, nothing interrupting the view. They are also less forgiving: the glass is doing all the work, so they need a genuinely flat, level stand and a mat underneath. Braced tanks are cheaper and more tolerant of an imperfect stand, at the cost of the trim in your eyeline.
Before it goes on the stand
Water weighs about 8.3 pounds a gallon before you add substrate and rock — a filled twenty-gallon is comfortably over two hundred pounds. Check what it is going on. Level it properly. And if the tank is going anywhere near a wall, leave clearance behind it for a filter and for your hands.
Setting up your first one? Start with our guides.
