This paper presents an overview of the current knowledge about species diversity and morphological taxonomy of the Colombian conchostracan fauna. Relationships among morphological variability, reproduction biology and environmental conditions are stressed. The Colombian fauna includes 12 species in five families: Limnadiidae Sars, 1896; Leptestheriidae Daday, 1915; Cyclestheriidae G. O. Sars, 1899; Metalimnadiidae Straškraba, 1965; and Lynceidae Stebbing, 1902. No member of the families, Cyzicidae Stebbing, 1910, or Imnadiidae Botnariuc & Orghidan 1941 have been found in Columbia. Morphology depends on developmental stage and on the modulating effects of environmental conditions. Extremely high temperatures may lead to specimens with neotenic features inEulimnadia magdalenensis Roessler, 1990.