How many gallons of water does a twenty gallon fish tank hold? - Answers

a 20 GALLON tank does have a capacity of 20 gallons. Hope you have a great time with your spacious (to me at least) aquarium, i have a 5 gal. because that is all i can support and afford right now, for a 20 gal. i would recommend schooling tropical fish like tetras, danios, guppies, swordtails, scissortails, gouramis, ect." ok for the weight, if you have a 20 gallon tank with NO decorations or substrate in it ( sand/gravel it weighs 225 pounds! now mind you everything you put in your tank, takes up space. on average you will put 2 inches of substrate on the bottom of the tank, witch weighs about 22-25 lbs depending on the substrate your using. so there is 25lbs of water being displaced. now you have your heater, any air bubblers, decorations/plants and of course fish. everything you put in your tank takes up space. so realistically your looking at roughly 15 - 17 gallons ( US, not imperial as even in Canada here the aquariums are sized by US gallon and not Imperial) of water in your tank. ( or roughly 64.26 liters based on 17 gallons..weighting in at 8.321 lb per pound is about 141 pounds.) So make darn sure whatever your putting the tank on can continuously hold 200+ pounds. if that falls off the stand you will know it. im sure the floor wouldn't appreciate the sudden weight dropped on it or the 75.6 litres of water now cascading around the room, down your heater vents or down your stairs! it holds 20 gallons of water