Conditions have been optimised to transfect the fish cell line CHSE-214 to measure expression, maintenance and putative chromosomal integration of the reporter gene LUC, spliced into two versions of an expression vector. The first is pCMVL, and the second p103, a novel pCMVL-derived plasmid to which a highly conserved tandem repeat from the salmon genome was added in an inverted configuration flanking the LUC gene to promote its chromosomal integration. A minimal ratio of one to one, lipopolyamine carrier to plasmid DNA, was enough to efficiently transfect the cell line to follow the fate of target DNAs up to five cell passages. In this time-span we demonstrated the maintenance of the foreign DNA in the cells, the concomitant expression of the reporter gene, and a higher stability of p103 over the control plasmid which might suggest a higher potential for integration. Thus, we define an efficient model system for future in vitro evaluation of potential target genes of commercial interest for fish transgenesis.