8 Cuadernos de Biodiversidad ABSTRACT Galicia (NW Spain) has a dense river network constituted by small coastal rivers, which present a high number of freshwater endemics. However, in the last two decades there has been a steep increase on the records of freshwater invaders on the region, and these constitute an important threat for its freshwater biodiversity. Most of the exotic species present in Galicia have been previously recorded in other areas of the Iberian Peninsula. Te temporal analysis of the evolution of the records of invasions in Galicia and in the rest of the Iberian peninsula, shows that the tendency adjust to a decreasing linear regression, with species introduced after 1995 in F. Cobo 1, 2 , R. Vieira-Lanero 2 y M. J. Servia 3 1 Departamento de Zooloxía e Antropoloxía Física, Universidade de Santiago de Composte- la. Campus Sur s/n, 15MX2 Santiago de Compostela, Spain. 2 Estación de Hidrobioloxía “Encoro do Con”, Castroagudín s/n, 3661M Vilagarcía de Arou- sa, Pontevedra, Spain. 3 Departamento de Bioloxía Animal, Bioloxía Vexetal e Ecoloxía. Facultade de Ciencias. Uni- versidade da Coruña. Campus da Zapateira s/n. 1500X A Coruña, Spain. other Iberian areas being almost immediately pre- sent also in Galicia. Detailed analysis of pathways of introduction underlines the important role of aquarium trade on these results, which needs to be regulated if we want to stop or at least retard the introduction of new invasive species on freshwater habitats. KEY WORDS: Invasive species, freshwater, Galicia, Iberian Peninsula, aquarium trade. Turistas indeseados. Ritmo de entrada de especies exóticas en los medios acuáticos gallegos en el último siglo