A shoal of adult Atlantic mollies, P. mexicana (left arrow, 1), as well as another poeciliid (Heterandria bimaculata; middle, 2) in close proximity to a group of C. salvini (right, 3). Note that the mollies showed no obvious fright response. The photo was taken at a site in a clear-water affluent to the "El Azufre", a sulfidic stream in the Cueva del Azufre system . Traces of calcium sulphate give the water a milky appearance.
Bierbach et al. BMC Evolutionary Biology 2011 11:190 doi:10.1186/1471-2148-11-190