Of uncertain origin.
Central Indo-European word for "fish" *dǵʰuH- (“fish”) (yielding Ancient Greek ἰχθύς (ikhthus), Lithuanian žuvìs, Old Armenian ձուկն (jukn)) would have given Proto-Slavic v-stem **zy (genitive **zъve, accusative **zъvь), and was, as the theory goes, avoided by fishermen due to taboo, or because it would've sounded too similar to the verb *zъvati (“to call”).
Some of the proposed etymologies include:
- From Early Proto-Slavic *rūmbā (with the loss of medial *-m-), which is then comparable to *rębъ (“speckled, motley, variegated”), with fish scales being the semantic connection. For a similar development compare *pьstry (“salmonid fish”), originally "the colorful/variegated one" < *pьstrъ (“variegated”).
- From the Early Proto-Slavic root *ūr- (“water, swamp, pond”) which is attested in Baltic languages, with a rare metathesis and the suffix *-ba for forming abstract nouns.
*ry̋ba f (accent paradigm a)
- East Slavic:
- South Slavic:
- West Slavic:
- Alemko Gluhak (1993), Hrvatski etimološki rječnik, August Cesarec: Zagreb, page 526
- “рыба” in Max Vasmer (1986), Etimologičeskij slovarʹ russkogo jazyka [Etymological Dictionary of the Russian Language], in 4 vols (second edition), Moscow: Progress — Translated from German and supplemented by O. N. Trubačóv