The Rio Grande silvery minnow is one of the most endangered fish in North America, according to the U. S. Fish and Wildlife Service (USFWS). It was classified as endangered in the U.S. in 1994 and now is found in less than 5% of its natural habitat in the Rio Grande. Historically, the minnow was found from Española, New Mexico, to the Gulf of Mexico in Texas. Now, it can only be seen between Cochiti Dam and Elephant Butte Reservoir. It can also be found in a small pond in North Carolina.
Description
It is a stout, silvery minnow with moderately small eyes and a small mouth. Adults may reach 3.5 in (89 mm) in total length.
Diet and behavior
Rio Grande silvery minnows are herbivores whose diet is believed to consist of river plants and benthic macroinvertebrates, though little research has been conducted into their diet due to the difficulty of getting into their stomachs. They play a role in keeping water clean by eating algae.
Silvery minnows tend to skim the bottom of rivers and streams and are prolific spawners. They serve as food source for other animals.
Reproduction
The Rio Grande silvery minnow's eggs hatch in about 24 hours into larvae that can swim in just 3 to 4 days. A species so programmed for survival, unsurprisingly, once dominated a biological niche that spanned roughly 3,000 meandering miles (4,825 km) in New Mexico and Texas.
Classification under the Endangered Species Act
The Rio Grande silvery minnow was first listed on July 20, 1994. It is currently designated as endangered in its entire range. The population decline of the Rio Grande silvery minnow has been almost directly proportional to recent alterations to the Rio Grande over the past century. Multiple diversions for municipal and agricultural uses have occurred, including alteration of the natural hydrograph (no spring runoff to cue spawning), habitat degradation from river narrowing and canalization, and construction of diversion dams that prevent migration. Even with the minnow's listing in 1994, its population has continued to drop at a great rate. Minnow numbers are now considerably below their 1994 population, and the Rio Grande silvery minnow is found in only 5% of its former habitat.
Alterations of the Rio Grande include not only the modification of the flow of water by dams and channels, but also the unintentional pollution of the water, which can originate from many factors, the major ones being effluents by the military and industrial companies and wastewater from nearby cities and towns.
Restoration efforts
In 2000, the USFWS initiated a silvery minnow egg salvage pilot project. Biologists from the service, Bureau of Reclamation, and University of New Mexico collect minnow eggs and reproductively ready adult minnows near Elephant Butte, where these efforts do not disturb upstream populations. Captured adult minnows are induced to spawn, either at the Albuquerque Biological Park or the USFWS's New Mexico Fishery Resources Office. Biologists then either return the resulting fry to the Rio Grande or hold them for captive propagation.
The silvery minnow refugium
as taken from the Van H. Gilbert Architect PC official page:
Article text: Wikipedia contributors, Rio Grande silvery minnow (source revision). Licensed under CC BY-SA 4.0. Retrieved 2026-10-11.
