Happy Fish Friday, everyone!
I want to toss a splash of color into your day after these winter storms pass through. This week I give you the Western Blacknose Dace (Rhinichthys obtusus). Their defining characteristics are having a moderately long and stout body, a flattened head and belly, and small body scales. Their backs and upper sides are olive to dark brown with darker scales that are scattered making them appear mottled. They have a dark lateral band that runs along their body, around their snout, to the caudal (tail) fin.
Male Western Blacknose Dace from a headwater stream in northeastern Illinois. Credit: Paul DeRolf
The Western Blacknose Dace is often referred to as a “riffle dace.” This nickname is because their preferred habitat is swift current in small, high-gradient streams. These streams are clear with silt-free substrates comprised of gravel, cobble, and bedrock. The healthiest populations of Western Blacknose Dace are often in areas with a forested riparian zone and well-developed riffle-pool complexes. They will also utilize root wads, undercut banks, and woody debris as cover to escape predators or high flows.
Comparison of Western Blacknose Dace (top) and Southern Redbelly Dace (bottom). Both are often found together in small schools. From a headwater stream in southern Ohio. Credit: Paul DeRolf.
Their diet is primarily aquatic insects that live on or underneath the rocks. As adults, they have been known to be opportunistic and eat the eggs of other fishes that are found in shared habitats. They use their flattened head to get into the interstitial spaces (open space of stream bed) between the rocks.
Spawning for the Western Blacknose Dace occurs in late-spring to mid-summer, depending on water temperatures. Come time for mating, the males will develop small tubercles on top of the head and pelvic fins (similar to fine sandpaper), their lateral band will turn bright red, pink, or rusty-red, and their fins turn yellow, while females develop a gold stripe along their body. Males establish and defend small territories over riffles. Once the eggs are laid and fertilized, they are buried into the substrate where they remain unguarded.
Male Western Blacknose Dace showing his spawning tubercles (white bumps on head) from the Little Blue River, IN. Credit: Paul DeRolf.
Once considered a single species, the Blacknose Dace eventually was split into the Eastern and Western Blacknose Daces around 2004. This split, for the most part, follows the Appalachian Mountains. Easterns are on the Atlantic Slope, and Westerns make up the rest of the range. There are some places where they overlap. Western Blacknose Dace are primarily in the Upper Mississippi and Ohio River drainages. There have been some findings of these fish outside of their native range, in the west. The causes for these occurrences aren’t known but are thought to be bait bucket releases. If there are established populations of Western Blacknose Dace, there are currently no known impacts on the native assemblages. *Even though they are common, please do not transplant these or any other species outside their current range.*
Range map for Western Blacknose Dace. Map Credit: fishmap.org
Western Blacknose Dace were at one point, and possibly still are, a popular baitfish used by recreational anglers. This popularity lead to a significant decline in their populations during the mid-1900s. Since then, they have bounced back and made an excellent recovery. Now there are even more ways to see them. Because of their schooling behavior and aggressive eating habits, they can be caught while microfishing or seining. Thanks to their large personalities and bright colors, they make for some of the best fish in a home aquarium. They will stay active and colorful as long as you provide them with good flow, a rocky bottom, and a natural diet. No matter how you decide to see them, please remember to make sure that you enjoy, protect, and enhance our freshwater ecosystems!
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