Variations: Öfug-uggi, Reverse-Fin Trout, Fin; Afuggafiskur, Aufuggufiskur (meanings unclear)

The Öfuguggi or Reverse-Fin Trout is one of several Icelandic fish distinguished by an extreme toxicity. Its poisonous reputation is such that its name has entered common Icelandic as a slur for jerks, perverts, loners, and homosexuals. The stories told of it are identical to those of the shaggy trout, and the two fishes are commonly confused. Accounts of this lethally poisonous fish date to before the mid-17^th century.

As the name suggests, an öfuguggi looks deceptively like a normal brown trout with the exception of reversed fins and swimming organs, although Jónas Hallgrímsson specified in 1841 that only the small adipose fin is reversed. The öfuguggi swims backwards with its tail first and the head following; in color it is jet-black or coal-black. The flesh is red, indicating that the fish feeds on the bodies of drowned men.

Reverse-fin trouts live in the cold depths of freshwater lakes. There they are sometimes fished, prepared, and eaten – causing the deaths of all who tasted the meal. Öfuguggi poisoning may cause the victim to swell up until their stomach bursts, producing a cross-shaped wound. The most infamous poisoning incident is that of Kaldrani farm, where almost everyone on the household took ill and died after a meal of trout. The only survivor was a pauper girl who had no appetite at the time.

There have been sightings and tragic tales of the reverse-fin trout across Iceland. Known place names include Öfuguggatjörn (Reverse-Fin Pool), the vanished Öfuguggavatn (Reverse-Fin Lake), and Ofuggugavatnshaeðir (Reverse-Fin Lake Hills).

References

Davidsson, O. (1900) The Folk-lore of Icelandic Fishes. The Scottish Review, October, pp. 312-332.

Hlidberg, J. B. and Aegisson, S.; McQueen, F. J. M. and Kjartansson, R., trans. (2011) Meeting with Monsters. JPV utgafa, Reykjavik.

Pálsson, G. (1991) Coastal economies, cultural accounts: Human ecology and Icelandic discourse. Manchester University Press, Manchester.