An eclectic encounter: ticks feeding on an electric eel and the untapped potential of natural history collections.

Parasites are quite likely the most diverse guild of species on earth. Nevertheless, they remain under-documented despite their impact on the health and ecology of nearly every other species. Natural history collections offer a powerful, underutilized resource for uncovering the hidden diversity of parasites, particularly by preserving specimens that reveal unexpected host-parasite associations. Ticks, although known for their broad host range among terrestrial vertebrates, have never been documented parasitizing fish. Here, the author reports the first known instance of ticks associated with a fish host: 2 female Amblyomma sp. ticks were discovered on an electric eel, Electrophorus varii  de Santana et al. 2019. One specimen was removed and identified as Amblyomma cajennense sensu stricto (Fabricius, 1787). While likely an instance of opportunistic feeding, this collection record nonetheless greatly broadens the known feeding habits and associations between ticks and their hosts. This observation highlights the value of museum collections in revealing rare interactions that challenge established understandings in host-parasite ecology.