assfish

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• ass fish, ass-fish

From ass +‎ fish, probably from a mistranslation of onus in the genus name Acanthonus, which is from Ancient Greek ἄκανθος (ákanthos, “acanthus”, literally “prickly flower”) + ὄνος (ónos, “hake”): the latter word can mean either an ass (donkey) or less commonly a type of fish.^[1]

This etymology is incomplete. You can help Wiktionary by elaborating on the origins of this term. only explains the Acanthonus sense

assfish (countable and uncountable, plural assfish or assfishes)

1. Any of several types of fish:
   1. bony-eared assfish, Acanthonus armatus
   2. cavernous assfish, Porogadus gracilis
   3. any of various species in the genus Bassozetus:
      1. robust assfish, Bassozetus robustus
      2. abyssal assfish, Bassozetus compressus or Bassozetus elongatus

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