The purpose of this work was to examine the population structure and reproductive fitness of Pseudione elongata africana while parasitizing the shrimp Palaemon concinnus. About 100 hosts were sampled every 15 days for 12 months in two wetland ecosystems of similar ecological traits in Mozambique: a peri-urban mangrove, Costa do Sol and a pristine mangrove located at Inhaca Island, Saco. Parasites were removed from the branchiostegite of the host and measured. Ovigerous females were identified, eggs or embryous present in the female brood pouch were removed, their stage of development identified and counted. At the peri-urban mangrove, female parasite total length (FPTL) increased about 17% and frequency of ovigerous females increased from 28% to 50%, when compared to populations inhabiting the pristine location. Average brood size ranged from 89 to 207 eggs.mm-1 of FPTL at Saco mangrove while at Costa do Sol this value ranged from 177 to 357 eggs.mm-1. This work is considered a base line study to better understand parasite population structure and reproduction in East African mangroves. Also, comparison of this parasite structure and fitness in one peri-urban and one more isolated mangrove may lay the ground of using parasite reproduction as an indication of habitat anthropogenic pressure.