The abundance and sexual maturity of piangua Anadara similis in La Plata Archipelago, Bahía Málaga, Pacific coast of Colombia, was analyzed between September 2009 and August 2010. Sexual maturity of these organisms was studied at macroscopic level using fresh samples and at microscopic level using standard histological techniques. The mean density was estimated in 0.130 ± 0.098 ind/m2 and the mean size was 42.30 ± 5.00 mm. Months with the presence of the highest densities of piangua were May (0.295 ind/m2) and August (0.195 ind/m2). The mean sexual maturity size was estimated in 41.8 ± 4.5 mm, while the size at which at least 50% of the population of A. similis have had its first spawn was estimated in 41 mm. Reproductive activity of the species was present year-round with higher peaks in March (83.33%) and April (75.00%). 4.30% of organisms analyzed showed signs of hermaphroditism, being this the first record of this kind for the species. Higher density, larger mean size, higher meat yield in females as well as the presence of more female reproductive tissue, suggest a process of sexual reversion in the species, which have to be further studied. Low capture and sexual maturity sizes, as well as the low density of organisms found during the present work, might be the product of high fishery pressure, habitat modifications, and pollution processes in the area, factors that have to be studied in detail in order to implement management strategies for the species.