The Central Stoneroller (Campostoma anomalum) was described in 1820 by French biologist Constantine Samuel Rafinesque. Campostoma is Greek for "curved mouth," and anomalum means "extraordinary," describing the unique mouth that these fish possess. Central Stonerollers are in the same family as minnows and shiners, but they are often easily distinguished from their cousins. Their mouth position is similar to that of Suckers, but differ in that they have a hard, cartilaginous ridge inside their lower lip. This resemblance earned them the name "Rough-Nosed Sucker" back in 1838 by J. P. Kirtland (Rice and Zimmerman 2019). They have been reported to reach max lengths of 22 cm (roughly 8.6 inches). These interesting little fish are a top live bait choice used by anglers going after Muskie or Muskellunge.
A male Central Stoneroller in spawning condition from the West Fork White River, Indiana.
Central Stonerollers live in headwater streams up to large rivers that are moderate- to high-gradient. When in creeks and small rivers, they prefer riffles and runs with fast-moving water over sand and gravel substrates, but can be found utilizing pools with swift current. In larger rivers, they will be confined to the riffles and shallower runs, avoiding the pools due to the slow-moving water. Central Stonerollers are known as a benthic species, meaning they live on or near the bottom of their home streams.
A healthy, gravid female Central Stoneroller from the Little Blue River, IN.
The primary forage is aquatic vegetation, algae, and occasionally aquatic insects. Central Stonerollers are considered to be herbivores due to the high amount of organic matter that has been found within their digestive systems. They feed by using the cartilaginous ridge on their lower lip as a chisel or scrapper. They will go along the bottom, use their tail fin to propel them forward, and peel algae off of the rocks. This feeding behavior is what allows them to easily eat insects. As they feed on the algae, they will accidentally pick up the insects that reside on or within that vegetation.
A male Central Stoneroller displaying large tubercles during the breeding season. Picture credit: Tyler Goodale.
The spawning season for Central Stonerollers begins in the early spring and goes until the summer, varying from region-to-region. Males pick an area in slower water, often above or below a riffle, with gravel or pebbles as the main substrate. They will dip pits in the substrate by using their mouth to pick up rocks and move them outside of the nest or roll the objects out by pushing them with their heads. As the season progresses, males intensify in color with their fins enhance with orange and black, their bodies become a bright yellow-tan, the lips grow and turn a livid white, and they develop large protrusions on their head and along the body. These protrusions are known as tubercles and they are thought to serve two purposes: the first, they assist in protecting the nest from other males by acting as pointy body armor; the second, they act as "body jewelry" to attract females.
The image from FishMap shows the wide range that Central Stonerollers cover. They extend north into North Dakota down to southwestern Texas, west out to central Wyoming, and as far east as New York. The grey watersheds indicate where they currently occur and the red are their historic watersheds. These fish are not threatened or endangered in any part of their range and are considered of "least concern." They are tolerant to siltation of the substrate but are intolerant to most pollutants. One of the pollutants they are tolerant of is fertilizer runoff, and this is because it causes the algae cover to explode, creating more food supply for them to eat.
The best way to observe these fish is to find a stream with large mats of filamentous, green algae growing on rocky riffles. In these particular areas, you are likely to see schools of Stonerollers grazing on the algae. Fishing for them might be hard since they are herbivores, but you could get lucky and have one take a piece of red worm on a small hook. Snorkeling during the spawn would be very rewarding to see them digging and defending their pits. No matter how you choose to try and observe them, make sure to continue to enjoy, protect, and enhance our streams!
References
Rice, D., and B. Zimmerman. 2019. A Naturalist's Guide to the Fishes of Ohio. Special Publication of the Ohio Biological Survey. vii + 391 p.
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