Candida spp. Are the principal fungi responsible of many nosocomial infections. C. albicans is the most common isolate specie found in patients globally, but C. krusei is considered an emerging specie. Both C. albicans and C. krusei can form biofilms. The compound (PhSe)₂ is a promising biofilm inhibitor of both species separately. This research uses two mediums to form dual-species biofilm: RPMI-1640 and Sabouraud dextrose-broth (SDB). (PhSe)₂ was tested on biofilm adhesion and formation, as well as on mature biofilm. The XTT assay was used to determinate the metabolic activity of biofilms, and the product of them was quantified by absorbance at optical density of 490nm. It was observed a reduction in metabolic activity of dual-species biofilm produced using RPMI-1640, however no effect was observed in biofilms produced using SDB. These results demonstrated that the medium used to produce biofilms can modify the biofilm development and, therefore change the effect of antifungal agents.