Females.. The size difference varies in species. The larger the species the larger the difference between m and f.
Which species do you have/ are you looking to buy?
I'm pretty sure the female is always bigger. In most cases, but then again there are genes so the biggest male in the pool could have a crush on the smallest female, but if you take 1 male a female out of the same batch the female will be bigger.
Females.. The size difference varies in species. The larger the species the larger the difference between m and f.
Which species do you have/ are you looking to buy?