Large specimens of P. aztecus males attain an adult size of approximatley195 mm in length, while large female specimens may reach 236 mm in length (Williams 1955). Growth rates for juvenile P. aztecus in North Carolina were estimated by Williams (1955) to be 46 mm per month. In Louisiana, Wilson (1969) estimated growth rates ranging from 45 - 50 mm per month, with overall growth decreasing with age.Growth slows markedly when brown shrimp reach approximately 100 mm. Beyond this size class, male growth slows in comparison to female growth.