Clarias cavernicola or blind cave catfish, as it is called in English, is known only from one cave near Otavi in Namibia, where it lives in total darkness. It is classified as Critically Endangered by the International Union for Conservation of Nature (IUCN), the global authority on the status of nature and its species. The total population of catfish in the cave is probably less than 200 individuals, which is the minimum genetically viable population size required for any species to survive over a longer period of time. This makes the blind cave catfish one of the rarest freshwater fish species in the world. This little catfish species, which grows only up to 17 cm long, has lost its eyes. Additionally, it lacks the pigmentation that produces the normal dark skin colour of other catfish species, and is thus a beautiful golden-pink. In a dark cave, eyes and skin pigmentation are not necessary for survival, so it is likely that not producing these characteristics is part of the catfish's survival strategy. Conserving energy is especially important for survival when food is scarce. It seems that this rare catfish feeds mainly on invertebrates or insects falling into the cave. Another possible item on the catfish's menu is an isopod (a shrimp-like organism) that is also endemic to this cave and lacks colour and eyes. Our research team further speculates that the catfish uses guano from the bats in the cave to supplement its meagre invertebrate diet.