Consumers of mislabeled tropical fish exhibit increased risks of ciguatera intoxication: A report on substitution patterns in fish imported at Frankfurt Airport, Germany

A major challenge in the international fish trade remains to reliably discriminate hundreds of fish species from possible substitutes which are perhaps not recommended for consumption. Recurring instances of ciguatera fish poisoning in the EU were associated with the consumption of mislabeled imported tropical fishes, mostly the red snapper Lutjanus malabaricus. Because the underlying fish species substitutions were only brought to the public attention due to resulting severe disease symptoms of this foodborne illness, we suggested a significant dark figure of undetected species substitutions with associated health risks. For the first time, the species identity of 975 individual fish imported into the EU at Frankfurt Airport from various provenances was correlated with their potential risk to cause ciguatera intoxication over a three-year period. Based on DNA sequence analysis and supporting peer-review of specimen photographs an overall mislabeling rate of 31% was determined which varied massively between 0% and 100% across fish families. Even though the sampling was not strictly random, this suggests massive fish species substitutions already at early stages of the value chain in the EU and over long time periods. From a health risk perspective, the occurrence of ciguatera-prone species in the cohort of DNA-identified substituted fish was dramatically higher compared to the correctly labeled fish (46% vs. 17%). Since our sampling largely reflects standardized official import procedures on fish labeling, these numbers suggest that the import of mislabeled tropical fishes, in particular snappers (Lutjanidae) and groupers (Serranidae), poses an underestimated health risk for seafood consumers in Europe.