and on how big they get it depends
a NG frill is genrally smaller males will be about 2 feet and a female about 20"
then there are Australians which the males get about 3 feet and the females slightly smaller
no not at all
a baby could fit in a 20gallon
a juvinile should be in a 30 or 40 gallon
and the min for a single adult is 3feetwidex3feetlongx4feet high
I have my juvi in a 3widex4longx3.5high