Konrad Ostertag was born in 1718 in Mannheim (today in Baden-Würtemberg). He married Demuth (surname unknown), and they had at least the following seven children, each baptized in the Catholic Church in Böhl, southwest of Mannheim: (1) Johann Jakob (born 1748); (2) Johannes (baptized 7 May 1751); (3) Johann Ludwig (baptized 14 December 1752); (4) Anna Maria (baptized 1 November 1754); (5&6) twins Anna Margaretha & Johann Konrad (baptized 22 August 1757); and (7) Johannes (baptized 12 July 1760).
Konrad and his family immigrated to Russia, arriving from Lübeck at the port in Oranienbaum on 8 August 1766 aboard the snow-brig Der Merkur under the command of skipper Johann Heinrich Abelmann. The twins died sometime before they sailed for Russia, as only Konrad Ostertag, his wife Demuth and the other 5 children (Johann Jakob, Johannes, Johann Ludwig, Anna Maria, & Johannes) reached Oranienbaum.
Konrad's wife died during the journey between Oranienbaum and the Volga German colonies.
The Konrad and the children arrived in Sewald on 20 August 1767. They are recorded there on the 1767 census in Household No. 35.
Konrad died before 1798. His sons Johann Jakob and Johannes (b. 1751) moved to Dehler and are recorded there on the 1798 census in Households No. Dl23 & Dl38. Johannes (b. 1760) moved to Volmer and is recorded there on the 1798 Census in Household No. Vm29. There are no Ostertag descendants who remained in Sewald.
- Mai, Brent Alan. 1798 Census of the German Colonies along the Volga: Economy, Population, and Agriculture (Lincoln, NE: American Historical Society of Germans from Russia, 1999).
- Pleve, Igor. Einwanderung in das Wolgagebiet, 1764-1767 Band 4 (Nordost-Institut – 37805 Göttingen: 2008): 174.
- Pleve, Igor. Lists of Colonists to Russia in 1766: Reports by Ivan Kulberg (Saratov: Saratov State Technical University, 2010): 219.