The northern cavefish or northern blindfish (''Amblyopsis spelaea'') is found in caves through

Kentucky Kentucky (, ), officially the Commonwealth of Kentucky, is a landlocked U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders Illinois, Indiana, and Ohio to the north, West Virginia to the ...

and southern

Indiana Indiana ( ) is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders Lake Michigan to the northwest, Michigan to the north and northeast, Ohio to the east, the Ohio River and Kentucky to the s ...

. The

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...

lists the species as near threatened. The life cycle of northern cavefish includes a protolarval stage. In this stage, eggs and those that have recently hatched into protolarvae are kept by the mother internally in a gill chamber. Juveniles become free swimming and can leave. The northern cavefish lives to a maximum age of at least ten years and reaches sexual maturity at approximately six years of age. Some estimates suggest that speciments may live up to 30-40 years in environments with stable food supplies. During a 2013 study of ''Amblyopsis spelaea'', scientists found that the species was divided into two distinct evolutionary lineages: one north of the

Ohio River The Ohio River () is a river in the United States. It is located at the boundary of the Midwestern and Southern United States, flowing in a southwesterly direction from Pittsburgh, Pennsylvania, to its river mouth, mouth on the Mississippi Riv ...

, in Indiana, and one south of the river, in

. The southern population retained the name ''A. spelaea'' and the northern was re-designated '' Amblyopsis hoosieri'' in a 2014 paper published in the journal ''

ZooKeys ''ZooKeys'' is a peer-reviewed open access scientific journal covering zoological taxonomy, phylogeny, and biogeography. It was established in 2008 and the founding editor-in-chief was Terry Erwin (Smithsonian Institution The Smithsonian ...

''. Neither species is found north of the White River, flowing east to west south of Bedford, Indiana. The northern cavefish was under consideration for listing under the

Endangered Species Act The Endangered Species Act of 1973 (ESA; 16 U.S.C. § 1531 et seq.) is the primary law in the United States for protecting and conserving imperiled species. Designed to protect critically imperiled species from extinction as a "consequence of e ...

, however, the U.S. Fish and Wildlife Service found in 2023 that despite the loss of two metapopulations of ''A. spelaea'', listing was not warranted, as the four metapopulations that still exist had sufficient redundancy of subpopulations to mitigate threats. The metapopulations are divided among two units that are separated by the Rough Creek Fault Zone. Threats to the species include habitat degradation, especially by groundwater contamination from encroaching agricultural operations, cities and industry, forest loss and surface water impoundment.

References

* {{Taxonbar, from=Q2842127 Amblyopsidae Cave fish Cavefish, Northern Fish of the United States Fish described in 1842 Taxa named by James Ellsworth De Kay Mammoth Cave National Park