There are two variations of Ruda, Sjöruda and Dust Ruda.
It thrives in both flowing and still water, fresh and brackish.
Rudan in Skåne, Blekinge, Gotland (among others Tingstäde swamp, Storsund and Fardume swamp), Bohuslän, Dalsland (10 lakes), Vänern, Västergötland, Närke, Västmanland, Södermanland (Trehörningen in Huddinge sn), Värmland, Dalarna, Jämtland and from Småland coast north into Norrbotten, where it is found in some lakes at the marine border in the Pajala and Junosuando snr, as well as in the Baltic Sea and the Gulf of Bothnia archipelago.
It is very tenacious and can handle many different environments. Although it is a warm water fish can survive in lakes in Lapland by lying and pressing against the mud at the bottom of a lake that is not frozen. Rudan can play hike up from coastal brackish water to fresh water and back again.
The species can be over 40 years.
Swedish record: 2.8 Kg.