Blind Mexican Tetra Fish

Blindness in the Mexican tetra fish is a controversy among scientists whom have long-debated the mechanism of this evolutionary change. The Mexican tetra fish, Astyanax mexicanus, exists in two morphs: a sighted surface form and a blind cavefish form. The debate amongst scientists is rooted in the process by which the Mexican tetra became blind. Evolution demands progress, yet the blind Mexican tetra suggests regression, as it lost its vision over time.
However, through the continuous studies of the blind Mexican tetra fish, scientists now realize that the purposeful loss of vision was triggered by a protein, HSP90, when the ancestors of the Mexican tetra were thrust into an undesirable environment – a pitch black cave. The variability present