Etymology

From Proto-Balto-Slavic *źuˀs; related to Latvian zivs, Old Prussian suckis ‎(“fish”). From Proto-Indo-European *dʰǵʰu- ^[1]; cognate with Ancient Greek ἰχθῡ́ς ‎(ikhthū́s), Old Armenian ձուկն ‎(jukn, “fish”).

Since *dK- regularly yielded *iKt- in Greek (compare ίκτῖνος ‎(íktînos), ἑκατόν ‎(hekatón)), Proto-Indo-European *d- as opposed to *dʰ- must be reconstructed, encouraging a connection with the root *deǵʰ- ‎(“liquid?”); compare Old Irish deug ‎(“drink, draught, potion”), Lithuanian dažaĩ ‎(“paint, dye”). A similar semantic path can be observed in ūdra ‎(“otter”) from *wed- ‎(“water”) ^[2]