Eye regression variations within the El Refugio population. In the figure, we can observe from entirely absent eyes (A–C), to different levels of vision regression (D–F). Regarding the body and eye regression combined we also observed a wide variation G, H eyeless and small-eye fish without pigment I, J eyeless and eyed fish with yellow pigment, and eyeless fish with a caudal black spot (K) L eyed and black spot and yellow pigment in the caudal fin.