How much litres of water would I need for 1 neon tetra/white cloud/zebra fish?

a ten gallon tank will be more then sufficient. Looks dumb when you have a 50 gallon tank with 3 fish in it. you could do like a dozen neons, a couple of white clouds and a few zebras in a 30 gallon tank, with a bunch of live plants and black or brown gravel, cheap and will look very nice.