Specimens of king tarakihi from northern New Zealand were shown to differ from specimens of tarakihi, using two genetic methods: allozymes and random amplified polymorphic DNA (RAPD). Allozyme techniques revealed fixed differences between tarakihi and king tarakihi at one locus and very different electromorph frequencies at a further three loci. There was a genetic distance of 0.35–0.39 between the two morphs. RAPD markers were generated with 10‐base oligonucleotide primers. Three out of 9 primers produced different DNA fragments in tarakihi and king tarakihi collected on the same longline, indicating that the morphs are discrete species. The two morphs could not be distinguished by conventional isoelectric focusing of muscle proteins. We conclude that the king tarakihi is a previously undescribed species found in subtropical waters of northern New Zealand.