Proto-IE: *leuk(')-
Meaning: a k. of fish
Old Greek: lêu̯ko-s m. N. eines unbek. Fisches, leu̯kísko-s m. `weisser Mullus'
Latin: lūcius, -ī `Hecht'
Russ. meaning: рыба sp.
References: WP II 408 f
Comments: Seems to be a derivation from #2341 *leuk'- 'to shine; white, bright'