Fish-based remedies in Spanish ethnomedicine: a review from a historical perspective

Background: Fish-based therapeutics is fundamentally based on a dietary use, but these vertebrates have also been employed in the treatment of infectious and parasitic diseases, during pregnancy, childbirth and postpartum and to deal with diseases of the different systems. Methods: An overview of the ethnomedical and historical Spanish literature has been carried out. Automated searches in the most important national and international databases have been performed. All related works have been thorough examined. Results: We examine the historical use of 54 medicinal fish species, 48 marine and six from inland waters. As useful, in Ancient times 39 species have been recorded (of which only 21 have been collected in subsequent periods), seven in the Middle Ages, 18 in Modern times and 17 in the contemporary period. Anguilla anguilla, Engraulis encrasicolus or Scyliorhinus canicula are species that have survived over time as an ingredient in Spanish folk remedies. Most remedies used in the last century and currently are empirical remedies based on the humorism theory and the principle of contraria contrariis curantur (74%), and the rest (26%) are magical type remedies that complete the popular therapeutic arsenal. Conclusions: In the last century we find a progressive decrease in the number of fish species used in ethnomedicine. Only seven taxa have been documented as surviving therapeutic resources since centuries ago. The existence of a dynamic Spanish ethnomedicine has also been detected which has managed to generate new therapeutic resources in recent times. It is important to validate the remedies by ethnopharmacology and evidence-based medicine. In order to recover as much data as possible, it will be necessary to draw up an inventory of ethnoichthyological uses.