The Proto-Indo-European word *dʰĝʰu-
Word *dʰĝʰu-
Meaning fish
See also Armenian: jukn ‘fish’
Greek: ἰχθύς ‘fish’
Euphratic: *ku ‘fish’
Synonyms *peisk, *dhĝhuhₓ-, *pik̂sk̂os

Comments
Lith. žuvis, Ltv. zivs, Arm. dzukn/dzuk/cug, Gk. ikhthus, Old Prussian suckis

Other words that might be of interest
*k̂on- ‘shell’, *laks- ‘salmon’, *karkr(o)- ‘crab’