The world is home to many rare fish species, but which are the rarest? Here are ten of the world's rarest fish: Desert Killifish, Wild Red-lipped Barracuda, Wild Chinese Sturgeon, European Eel, Maltese Ray, Bluefin Tuna, Mekong Giant Catfish, Scorpionfish, Flatfin Loach, and Great White Shark. These rare fish were once abundant, but due to unrestrained fishing and environmental destruction by humans, many now face the crisis of extinction. We should strengthen the protection of their habitats and raise public awareness of conservation to prevent their permanent disappearance.
1. Killifish (approximately 30)
The killifish is one of the rarest fish species in the world, having survived on Earth for over 60,000 years. It is primarily found in Death Valley, Nevada, USA, inhabiting small ponds of only a few dozen square meters. However, since 1960, agricultural irrigation has caused a drop in the water table, leading to a continuous shrinking of its habitat and a dramatic decline in its population. Statistics show that from approximately 400 killifish in the 1970s, only about 30 remained by 2019. Consequently, the killifish was among the first species listed in the U.S. Endangered Species Act in 1966.
2. Wild red-lipped barbs (approximately 100 or less)
The wild Chinese paddlefish (Pterodon spp.) is one of China's unique and rare freshwater fish species, and one of the world's ten rarest fish. In the past, they were widely distributed, found in most parts of the Yangtze River basin. However, due to overfishing, environmental pollution, and destruction of their spawning grounds, the wild Chinese paddlefish population has declined sharply and is difficult to control effectively. Furthermore, the long embryonic development cycle and high mortality rate during incubation also make it difficult for their numbers to recover. In the past 20 years, the number of wild Chinese paddlefish has been comparable to that of the Chinese sturgeon, thus facing the risk of extinction.
3. Wild Chinese sturgeon (approximately 100 individuals)
The Chinese sturgeon is the largest migratory fish in the Yangtze River and one of the world's rarest fish species, representing a flagship species. However, since the construction and operation of water conservancy projects such as the Gezhouba Dam, the Three Gorges Dam, and the Xiluodu Dam in 1981, the sturgeon's habitat and suitable water temperature environment have been blocked and destroyed, severely threatening its reproduction. Before the completion of the Gezhouba Dam in 1981, the Chinese sturgeon population was over 1,700, but by 2015, it had dwindled to only about 156. It is projected that by 2030, the Chinese sturgeon population will be reduced to less than 20, with zero males remaining.
4. European eels (approximately 250 or less)
The European eel is a rare fish native to the Atlantic Ocean. However, since the early 1980s, its population has declined by approximately 90%, and by 2019 it was listed as critically endangered, with fewer than 250 individuals remaining. Possible reasons for its decline include overfishing, parasitic infections (such as *Streptomyces coccidioides*), the construction of hydroelectric power plants, and environmental changes caused by natural factors such as the North Atlantic Oscillation, the Gulf Stream, and the North Atlantic Drift.
5. Maltese rays (50-250 or less)
The Maltese ray is one of the world's rarest fish species, now found only in the Strait of Sicily. However, its survival is precarious due to its shrinking habitat, slow growth, late sexual maturity, and very small offspring. Although not commercially fished, Maltese rays are easily caught and released back into the sea to fend for themselves, and local government conservation efforts have been slow, further exacerbating their plight. Currently, the Maltese ray is listed as Critically Endangered (CR) by the International Union for Conservation of Nature (IUCN), with an estimated population of 50-250 individuals, or even lower.
6. Bluefin tuna (50-250 or less)
Bluefin tuna is one of the largest tuna in the world and a staple fish in Japanese sashimi cuisine. However, due to its slow growth and overfishing, the population of this rarest fish in the world has drastically declined. EU fisheries experts warn that bluefin tuna could face extinction if fishing is not restricted; the International Union for Conservation of Nature (IUCN) has listed it as Critically Endangered (CR), the highest level of endangerment in the wild, estimating that only 50-250 individuals remain, or even less.
7. Wild Mekong giant catfish (50-250 or less)
The Mekong giant catfish is one of the world's rarest fish species, endemic to the Mekong River in Southeast Asia. However, due to overfishing, water pollution, and the construction of dams upstream, its wild population has drastically declined. To save this endangered species, fisheries departments in various countries have banned the fishing of wild Mekong giant catfish and established several artificial breeding bases, bringing the captive population to approximately 60,000. Despite this, the wild population of Mekong giant catfish remains extremely limited, and it has been listed as critically endangered (CR) by the International Union for Conservation of Nature (IUCN), with an estimated surviving population of between 50 and 250 individuals, or even lower.
8. Rare-spined rockfish (50-250 or less)
The Scorpionfish (Scorpionfish scutellatus) is a rare subtropical marine fish found in the eastern Pacific Ocean, from Alaska to Baja California, Mexico. They are olive-colored with brown and orange hues, have weak head spines, a long lower jaw, and thick lips. Scorpionfish can reach a length of 91 cm and primarily inhabit rocky bottom waters, feeding on crustaceans and fish. While they can be consumed as food and kept as ornamental fish, it's important to note that they are poisonous. Unfortunately, the Scorpionfish is critically endangered (CR) and listed as such by the International Union for Conservation of Nature (IUCN). Currently, the estimated number of individuals is between 50 and 250, or even lower, necessitating effective conservation measures.
9. Flat-finned loach (250-2500 or less than 250)
The flat-finned loach (Sinocyclocheilus 'Eight-Stripe') is a rare fish species endemic to my country, also known as the "eight-stripe whisker fish." Its distribution is limited to the main stream and tributaries of the middle and upper reaches of the Yellow River. In the 1950s, catching flat-finned loaches in the shallow waters of the Yellow River near Lanzhou was not uncommon. However, by the 1960s, due to water pollution, soil erosion, and increased sediment content, the river landscape had changed significantly, making it extremely difficult to find flat-finned loaches in the wild today. Currently, the flat-finned loach is listed as an endangered species by the International Union for Conservation of Nature (IUCN). Its exact population size is unknown, but it is estimated to be between 250 and 2500 individuals, or even lower.
10. Great white sharks (less than 3,000 individuals)
The great white shark is a well-known species, featured in numerous movies and video games, but its situation in the real world is dire. In fact, the great white shark is now one of the rarest fish species in the world. In the 1990s, due to rampant slaughter and fishing, 98% of great white sharks were killed for their fins and meat to supply the shark fin market. Because of their slow reproductive rate, their numbers have never recovered. As of 2019, there were fewer than 3,000 great white sharks left in the world, fewer than the number of wild tigers.
The list of the world's ten rarest fish species is primarily based on research into endangered species with limited populations, referencing data from authoritative magazines such as *Scientific American*. This list is for reference only; please feel free to comment and discuss any questions at the end.
