The Pyasachnik Reservoir () is located in the northwestern part of Upper Thracian Plain in southern central Bulgaria, along the river Pyasachnik, a left tributary of the Maritsa. It is situated northwest of the village of Lyuben in Plovdiv Province. The reservoir covers an area of 9.1 km<sup>2</sup> and has a volume of 206.53 million m<sup>3</sup>. Pyasachnik Reservoir was constructed in 1958âÂÂ1964. Its waters are used for the irrigation of about 270 km<sup>2</sup> arable land.
The reservoir is a popular fishing area. The International Game Fish Association world record for a grass carp caught on hook was set in Pyasachnik Reservoir in 2009 â .