This document specifies a method for the identification of single fish and fish fillets to the level of genus or species. It allows the identification of a large number of commercially important fish species using DNA barcoding. This method was validated on raw fish. Laboratory experiences indicate additional applicability to processed fish products, e.g. cold smoked, hot smoked, salted, frozen, cooked, fried, deep-fried samples. The described method is usually unsuitable for the analysis of highly processed foods, e.g. tins of fish, with highly degraded DNA where the fragment lengths are not sufficient for amplification of the targets. Furthermore, it is not applicable for complex fish products containing mixtures of two or more fish species. The identification of fish species is carried out by PCR amplification of either a segment of the mitochondrial cytochrome b gene (cytb) or the cytochrome c oxidase I gene (cox1, syn COI) or both, followed by sequencing of the PCR products and subsequent sequence comparison with entries in databases. The decision whether the cytb or cox1 gene segment or both are used for fish identification depends on the declared fish species, the applicability of the PCR method for the fish species and the availability of comparative sequences in the public databases. Two international DNA barcoding ring trials, the first using cytb and the second using cox1 gene segments, respectively identified 95 % and 87 %, of the tested samples to the fish species. All samples were correctly identified to the genus level.