Ozark minnow  (Notropis nubilus)

The Ozark minnow has not yet been classified by the IUCN.

A small, slender fish with an almost round body (2) (3), the Ozark minnow (Notropis nubilus) is dusky yellow to olive above, with dark-edged scales and a distinctive dark stripe that extends from the tip of the snout to a faint spot at the base of the tail fin. It has dull silvery sides and a silvery-white belly (3) (4) (5) (6) (7). The mouth is positioned at the tip of the blunt snout, and the Ozark minnow also has prominent eyes that appear large in proportion to the head (4).

Breeding Ozark minnows develop a yellowish-orange colouration on the underside of the body and on the fins (3) (4). Male Ozark minnows are more brightly coloured than the female during the breeding season, and may also develop pronounced tubercles on the head and fins (3) (6).

Found only in the U.S., the Ozark minnow occurs in the Red Cedar River system in northern Wisconsin and the Mississippi River tributaries in southern Wisconsin (8), as well as the Zumbro, Root, and Cedar rivers in southeast Minnesota (3). It is also found in north and central Arkansas (6), Iowa, Missouri and northeast Oklahoma (5) (8).

The Ozark minnow is most abundant in creeks and small-to-medium-sized streams or rivers with clear waters and gravelly or rocky bottoms. It is often found in pools and protected backwaters near riffles, in areas where the water is free of debris and vegetation (2) (7) (8) (9).

In most parts of its range, the Ozark minnow spawns between late April and early July, although it may continue through to early August in Wisconsin (2) (8). This species schools near the bottom of shallow waters, and often forms spawning aggregations numbering several hundred individuals (2) (3) (6) (8).

Spawning generally lasts for around one minute, during which time the Ozark minnow will vibrate vigorously against the substrate and other fish in the group (6). The eggs are often laid in or over the nests of the horneyhead chub (Nocomis bigguttatus) (6) (7) (8). 

The Ozark minnow feeds on a variety of algae and other plant material (2) (7) (8). Its diet may occasionally include small insect larvae and crustaceans (3).

Habitat degradation from heavy agricultural land use is the primary threat to the Ozark minnow (2) (3). This species is intolerant of excessive turbidity and siltation caused by pollution, sedimentation and agricultural runoff and, as a result, the Ozark minnow has declined in parts if its range (2) (9).

Many populations of the Ozark minnow are isolated from each other, meaning that this species is vulnerable to catastrophic events which may cause local population declines, such as natural disasters or disease (3).

Habitat degradation from heavy agricultural land use is the primary threat to the Ozark minnow (2) (3). This species is intolerant of excessive turbidity and siltation caused by pollution, sedimentation and agricultural runoff and, as a result, the Ozark minnow has declined in parts if its range (2) (9).

Many populations of the Ozark minnow are isolated from each other, meaning that this species is vulnerable to catastrophic events which may cause local population declines, such as natural disasters or disease (3). 

The Ozark minnow is classified as Threatened in Wisconsin (2).

Recommended conservation measures for this species include protecting and restoring its habitat, as well conducting further research on its status and biology (2) (3). Controlling pollution, erosion and agricultural runoff where the Ozark minnow occurs will also benefit its conservation (2).

For more information on the Ozark minnow:

• Wisconsin Department of Natural Resources:
  http://dnr.wi.gov/ORG/LAND/ER/biodiversity/index.asp?mode=info&Grp=13&SpecCode=AFCJB28680