Highly troglomorphic fish are found in the El Refugio cave and in the nearby well. The two fish in the insert were found in the well-used by locals to extract water. In this well, troglomorphic fish are seen swimming under the sunlight. The most troglomorphic fish in this cave system have two types of colorations, pink (A) and white (B). These two colorations are shown also in the specimens in the insert. Notice also that eye regression and skull modification create a downward hump in some specimens (red arrow).