If you will never be without a zero value then:
=SMALL(A1:A9,2)
Which picks the smallest number not = to 0 if zero is the smallest value in the range. [AKA the 2nd smallest number, zero being the 1st smallest number.] So, you cannot have negative numbers or these will be smaller than zero, giving a chance that zero now becomes the second smallest number!
So, your list must have at least one zero and cannot have any negative numbers.