Can algae fish live in a 2 gallon pond?

The basic rule for keeping any kind of fish is "1 inch of fish needs a minimum of 1 gallon of water." All fish tanks also need to have their water properly filtered to remove poisons created when a fish lives, breathes and poos in the water. No tank (pond?) is ever filled to the top so your nominal 2 gallon container is not big enough to keep any fish in without being cruel to the fish.