Choricystis is a genus of green algae in the class Trebouxiophyceae, considered a characteristic picophytoplankton in freshwater ecosystems.

[7][8] In particular, Choricystis has been proposed as a biological water treatment system for industrial waste produced by the processing of dairy goods.

[9] They have been observed as an endosymbiont of freshwater sponges as well as ciliates like Paramecium bursaria.

[10] Triglycerides and other lipids can be transesterified to produce fatty acid methyl esters, the primary component of biodiesel fuels.

[4][5][6][16][17] Molecular profiles of C. minor have noted its high proportion of neutral (as opposed to polar) lipids,[4][8][18][19] considered preferable in biodiesel production.