Leucism is a rare chromatic aberration, manifested by the total or partial absence of melanin in the skin. This study reports a case of leucism in the fish Lebiasina bimaculata (Characiformes: Lebiasinidae), in the Chongon river, Ecuador. The individual with leucism presented depigmentation all over the body, except in the iris and on the base of the third scale of the fourth longitudinal scale-series. With this case, there are 19 records of chromatic aberrations in South American freshwater fish.