Paramoebidium is a genus of unicellular, symbiotic eukaryotes that inhabit the digestive tract of immature freshwater arthropod hosts (e.g. black fly larvae, mayfly and stonefly nymphs).

[7] The prefix "para-", roughly meaning "similar to", refers to the assumed relatedness of Paramoebidium to the genus Amoebidium.

[7] The similarity of life cycle, morphology, and ecology lead to the hypothesis that Amoebidium and Paramoebidium were minimally closely related, and probably sister taxa.

The vegetative cells (= thalli) have an elongate, hair-like growth form with a secreted, glue-like holdfast at the base that attaches them to the host digestive tract lining.

For example, P. curvum[9] have short, coiled, thick thalli and are found in black fly larvae (Simuliidae), whereas P. hamatum[10] have relatively long thalli that are consistently curved near the base giving them a "candy cane" appearance and are associated mainly with mayfly nymphs (Ameletidae and Baetidae) but also midge larvae.