Koshlauch is a village (selo) in Arsky District, Republic of Tatarstan, Russia, located 24 kilometers (15 mi) north-west of Arsk, district's administrative center. The village is situated on the Krasnaya, Kazanka's right tributary. Population: 151 ; 137 (1989); all ethnic Tatars. The main occupations of the residents are agriculture and cattle breeding.