Kazanka or Qazansu (; ) is a river in the Republic of Tatarstan, Russia, a left tributary of the Volga. The Kazanka begins near the village of Bimeri in Arsk District and flows into the Samara Reservoir in Kazan, near the Kazan Kremlin. Other towns on the Kazanka are Arsk and historical Iske Kazan. The river is long. The main tributaries are the Iya, Kismes, Shimyakovka and Sula. Historically, the Bulak river flowed into Kazanka until it was separated by a dam in 1957. The maximum river discharge is , and the minimal mineralization is 400–1000 mg/l. In Tatarstan, Kazanka has a status of a natural monument.