Proto-Indo-European *bhel- "to shine" extended to *bhleg- became Greek φλόξ "flame" and phlogiston, the substance thought, in the 18th century, to exist in combustible substances and to explain why some substances burned and others didn't.
*bhel- became Russian белый belyj "white" and beluga. The suffix -уга/уха is, I think, an embiggening suffix.
Two more interesting derivatives are black, possibly from Proto-Germanic *ƀlakaz "burned", and bleach, from Proto-Germanic *ƀlaikjan "to make white" from *ƀlaikoz "white". This survived in Old English blāc "pale" and an obsolete word blake meaning "pale" or "yellow".