PCR-nucleic acid lateral flow immunoassay (NALFIA) with a combination of three primer pairs and two, respectively three, DNA template of Ostrea edulis, Crassostrea gigas, and Mytilus edulis. The label on the left side of every pair of cartridges is indicating the test line for the existence of O. edulis (FITC OE), C. gigas (632 CG), and M. edulis (495 ME). The most upper line on the cartridges is indicating the control line of each NALFIA. The combinations for DNA templates are O. edulis / C. gigas, O. edulis / M. edulis, C. gigas / M. edulis, with triple primer combination of OE / CG / ME primer pairs. OE and CG primer total concentration is 10 pmol μl⁻¹, and the total ME primer concentration is 50 pmol μl⁻¹. The cartridge on the far-left side shows the non-template control of the multiplex primer combination. Other cartridges are indicating the respective combination of the DNA template above. The image of the 3% agarose gel electrophoresis is showing the quality control of the NALFIA. The scheme of the gel slots: 1: 100 bp marker, 2: empty, 3: OE / CG / ME x non-template replicate 1, 4: OE / CG / ME x non-template replicate 2, 5: empty, 6: OE / CG / ME x O. edulis / C. gigas replicate 1, 7: OE / CG / ME x O. edulis / C. gigas replicate 2, 8: empty, 9: OE / CG / ME x O. edulis / M. edulis replicate 1, 10: OE / CG / ME x O. edulis / M. edulis replicate 2, 11: empty, 12: OE / CG / ME x C. gigas / M. edulis replicate 1, 13: OE / CG / ME x C. gigas / M. edulis replicate 2, 14: empty, 15: 100 bp marker, 16: empty, 17: OE / CG / ME x O. edulis / C. gigas / M. edulis.