Home and public sea aquaria are becoming more and more popular worldwide. Aquaria species are selected for their aesthetic appeal in terms of color, shape or behavior. In Brazil, most species are imported from remote places, usually tropical areas around the world. Water discarded from aquaria often includes organisms, or their propagula, that may become locally established. There have been extensive discussions concerning the vectors of species dispersion from their native areas, which includes ornamental aquaria. In order to evaluate the potential of local aquaria as a source of non native macro algae, we surveyed sea-aquaria shops and exhibition aquaria in Sao Paulo State. Thirty eight species of seaweeds were isolated in the aquaria surveyed. Among them, six have not been recorded from Brazil and nineteen were not reported for Sao Paulo littoral, including Caulerpa scalpelliformis var. denticulata the only species that so far deserves being designated as invasive in Brazil. The present paper should alert environmental agencies and aquaria shops about the risk of involuntarily introducing non-native species through aquariophyly.