DNA transfer to fish embryos allows the creation of genetically manipulated strains in commercial species and the in vivo study of gene expression of transient expression systems. Medaka and zebrafish have been widely utilized as model fish species, however accurate expression patterns from other different species can only be obtained when self specific systems are used. Due to high commercial value of the gilthead seabream species, a successful DNA transfer technique has been developed, to analyse the behaviour and the expression patterns of 'standard' plasmids in different conformations, with quantifiable (pCMV-CAT) and spatially (pCMVTtk-lacZ) detectable gene products. In this work it has been demonstrated that the gilthead seabream is a suitable system to test regulatory sequences from the own species. Additionally CAT and lacZ markers have proved to be respectively useful for quantification and spatial expression studies.