Pisidium stewarti is a species of small freshwater clam. It is an aquatic bivalve mollusc in the family Sphaeriidae, the fingernail clams and pea clams.

This minute clam, which is known in Europe as a decidedly Pleistocene glacial species, has also been identified as a Recent species in the Central Asian high mountainous massifs of Tien Shan, the Pamir Mountains and the Himalaya.

The recent distribution includes:

This article incorporates CC-BY-3.0 text from the reference