YaZ (Louciscos idus), yak nav mohist, ki dar obhoi shirini maskav giriftaast. Daroziash to 70 Sm, vaznash to 8 kg. Baroi Ya. daryo-sustjarayoni hamvori musoidand, dar kulho va obhoi shurtam (khal-hoi Botnik va Fin) niz vomekhurad. Ya. dar 3— 5 solagi bolig meshavad. Mohhoi apr.—may dar murdobhoi sohil (hangomi 3—6*S budani haror. ob) az 39 to 114 haz. tukhm (dar chuqurii 0,5— 0,7 m) meguzorad. Mohichahoi Ya. asosan zooplanktonhoro, mohihoi kalontar kirminai hasharoti obi. narmbadan (molyusk) -hoi mayda va kirmhoro mekhurand. Ya. dar qismi evropoii SSSR va Sibir ahamiyati muhimii sanoati dorad.