Semotilus atromaculatus

Geographic Range

Creek chubs ( Semotilus atromaculatus ) are widely found in eastern North America. Their range extends from Newfoundland through southern Canada to the Rocky Mountains, and points as far south as Florida.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

Creek chubs require flowing water for spawning and are often found in small headwater creeks, small streams, and agricultural ditches over gravel and sand substrates. They do not thrive in streams with strong continuous flow, as they are not able to compete successfully against larger fish species. They are able to tolerate moderately high turbidity as long as there is a sufficient amount of gravel substrate for spawning.

• Habitat Regions
• freshwater freshwater

• Aquatic Biomes
• rivers and streams

• Other Habitat Features
• agricultural agricultural

Physical Description

Adults are slender with a large dark spot at the front of the dorsal fin and a smaller dark spot at the base of the tail fin. Their total body length ranges from 12 to 18 cm (30 cm maximum). Anteriorly, the body is hardly compressed, but at the caudal end the peduncle is compressed. The head is broad with a short snout and has a large oblique mouth with a small barbel in the groove above the upper lip. Dorsally, they are dark olive with a dark strip along the midline; ventrally, they are white, with silvery sides. The fins are yellow to light olive with 8 to 9 dorsal-fin rays, 7 to 9 anal-fin rays, 13 to 18 pectoral-fin rays, and 8 pelvic-fin rays. Creek chubs are distinguished from similar species such as fallfish , cutlips minnows , and tonguetied minnows , by more lateral-line scales, and the anterior margin of the bottom lip being complete. Spawning males develop breeding tubercles (head, snout, fins, sides, and caudal regions), are brightly colored (apple-green above and rose-red below), and are larger in size compared to females.

• Other Physical Features
• ectothermic ectothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger
• sexes colored or patterned differently
• male more colorful

Development

Fertilized creek chub eggs develop within the nest with no parental care. Within six days after fertilization, the eggs begin to hatch. The newly hatched larvae have slightly decurved heads over a large yolk sac and are classified as being in the prolarvae stage. The end of this stage and beginning of the postlarvae stage occurs when the yolk has been absorbed and all fins except the pelvic fin are visible. The postlarvae stage lasts until the scalation, when the juvenile fish starts to resembles adult creek chubs. The entire larval stage lasts between 18 to 27 days.

Reproduction

Creek chubs are promiscuous, with multiple females visiting and laying eggs at a few different nests and males mating with several different females. Males construct pit nests (one male per nest) roughly 5.7 cm deep on the gravel bottom, near the lower end of the pool (where the current is quicker). Using their mouth, males dig a small trench (parallel to the course of the stream) and pile small stones upstream forming a ridge roughly 30 cm wide and 550 cm long. The male occupies and guards the completed nest, and often drives off other minnow species and smaller creek chubs. If they are challenged by a male of similar size, the two may engage in a ritual known as 'deferred combat'. The resident male arranges himself alongside the intruder and the two fish swim upstream for varying distances. At the end of their course, the two males settle to the bottom and bring their heads together, gently, and separate, with the owner returning to the nest. In addition to not being overly aggressive, the condition and locality of the nest is important for male reproductive success. While males construct nests, females wait nearby. During this time, they approach the male and his nest but usually flee once the male approaches. This behavior continues until one female does not feel intimidated and enters the nest. When a female enters the nest to spawn, the male takes up a position at the bottom of the nest near the lower end of the gravel ridge and waits for the female to be above him. The female can still be startled and flee, if this occurs, the male will pursue her and try to bite or hook her. When a female does not flee, the male throws her into a vertical position and her body is encircled by his body. The male’s opercle and pectoral fin are pressed against one side of the female, while his tail is pressed against her other side. This embrace lasts for no longer than a few seconds, during which, the female deposits her eggs. The female leaves the nest after depositing her eggs and another female may enter the nest and mate with the male. Once the male is done mating, he abandons his nest.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Male creek chubs grow at a faster rate than females. A majority of males reach sexual maturity at the age of 3 years. Sexually mature males develop breeding tubercles and change color, distinguishing them from females. Sexual maturity in females is also reached around the age of 3 years, but some females reach maturity after one year. The number of ripe ova per female correlates with the female's length. Mature ova are large and round (0.15 to 0.2 cm in diameter) and have a yellowish color, while immature ova are smaller and white (< 0.08 cm in diameter). Mating occurs for roughly two weeks, from mid-spring to early summer in waters with temperatures above 14° C. During spawning, males and females are found in fast shallow channels, with the males outnumbering females. Ripened females can lay between 500 to 4,000 eggs (depending on their age). If the female is large enough, she can go to another male's nest and lay additional eggs.

• Key Reproductive Features
• seasonal breeding seasonal breeding
• sexual sexual
• fertilization fertilization
  • external external
• oviparous oviparous

Neither the male nor the female are associated with providing parental care to their offspring.

• Parental Investment
• no parental involvement
• pre-fertilization
  • provisioning

Lifespan/Longevity

Creek chubs live 4 to 5 years, with a maximum lifespan of 8 years.

Behavior

Creek chubs are diurnal. They feed during the day after the water temperature has increased a few degrees. Larvae, however, are active throughout the day and are generally found in the shallow runs of creeks, streams, or agricultural ditches. They are often found among larvae from other fish species such as longnose daces and common shiners . Larvae seek shelter under vegetation and avoid deep areas to reduce the risk of predation. Juvenile creek chubs school with other minnow species such as pearl daces and brassy minnows . They occupy the edge of the pools and the deeper runs. Creek chubs that are larger than 1.8 cm generally do not school and occupy sheltered areas in deeper pools. They are active and instantly go towards any small object falling into the water. The majority of their time is spent near or underneath cover, only moving short distances from one cover area to another. Creek chubs winter in deep pools and runs.

• Key Behaviors
• natatorial natatorial
• diurnal diurnal
• motile motile
• social social

Home Range

Creek chubs can be very mobile, with movement both upstream and downstream. Their movement is related to resources and predation avoidance. Although they are very mobile and do change locations, their displacement distance is not great. On average their maximum range is 130 to 195 m but some travel up to 600 m.

Communication and Perception

Creek chubs mainly communicate visually. During the spawning season, males interact with other males and intruders through assessment of individual size, swimming patterns, and sometimes through physical contact. Possible chemical communication occurs when a cyprinid species is consumed or injured, releasing a pheromone alarm that is detected by creek chubs. If non-cyprinid fish and crayfish are abundant in the environment, then creek chubs avoid cyprinid species.

• Communication Channels
• visual visual
• tactile tactile
• chemical chemical

• Perception Channels
• visual visual
• tactile tactile
• chemical chemical

Food Habits

Creek chubs are generalized carnivores with a highly adaptable diet. They consume a small amount of plant matter, but this is associated with mutual consumption of its prey. In their first few months of life, they consume aquatic insect larvae. As they age, they consume adult terrestrial insects. Further growth leads to consumption of smaller fish, including other creek chubs, amphibians, crayfish, and mollusks.

• Primary Diet
• carnivore carnivore
  • eats terrestrial vertebrates
  • piscivore piscivore
  • insectivore insectivore
  • eats non-insect arthropods
  • molluscivore molluscivore
• omnivore omnivore

• Animal Foods
• amphibians
• fish
• insects
• mollusks

• Plant Foods
• leaves
• roots and tubers

Predation

Predators include larger fish such as brown trout , northern pike , and small mouth bass , as well as larger creek chubs.

Ecosystem Roles

Creek chubs are often found in different localities such as headwater creeks, streams, and in degraded habitats such as agricultural ditches, where they are found in great abundance. They are the top predator in most of these localities.

• Ecosystem Impact
• keystone species keystone species

Economic Importance for Humans: Positive

Creek chubs are economically important as they make excellent bait. The abundance of creek chubs in a given locality is increasingly used as an indicator of stream quality. Degraded sites tend to have high abundances, couple with a low diversity of other fish species.

• Positive Impacts
• research and education

Economic Importance for Humans: Negative

Creek chubs have become invasive in western states such as Wyoming. They compete, and in some cases outcompete native fish species such as roundtail chubs in Colorado.

Conservation Status

Creek chubs are abundant throughout their geographic range.

Additional Links

Encyclopedia of Life

BioKIDS Critter Catalog

Contributors

Zane Anderson (author), Indiana University-Purdue University Fort Wayne, Mark Jordan (editor), Indiana University-Purdue University Fort Wayne, Leila Siciliano Martina (editor), Texas State University.

References

Belica, L., F. Rahel. 2008. Movements of creek chubs, Semotilus atromaculatus , among habitat patches in a plains stream. Ecology of Freshwater Fish , 17.2: 258-272.

Buynak, G., H. Mohr. 1979. Larval development of creek chub and fallfish from two Susquehanna River tributaries. The Progressive Fish-Culturist , 41/3: 124-129.

Copes, F. 1978. Ecology of the creek chub. Reports on the Fauna and Flora of Wisconsin , 12: 21.

Dinsmore, J. 1962. Life history of the creek chub with emphasis on growth. Proceedings of the Iowa Academy of Sciences , 69: 296-301.

Jordan, M., P. Deepal, S. Kathryn, R. Gillespie. 2013. The relative roles of contemporary and ancient process in shaping genetic variation of a generalist fish in catchment dominated by agriculture. Freshwater Biology , 58: 1660-1671.

Lau, J., T. Lauer, M. Weinman. 2006. Impacts of channelization on stream habitats and associated fish assemblages in east central Indiana. American Midland Naturalist , 156/2: 319-330.

Magnan, P., G. FitzGerald. 1984. Ontogenetic changes in diet activity, food habits and spatial distribution of juvenile and adult creek chub, Semotilus atromaculatus . Environmental Biology of Fishes , 11.4: 301-307.

Michael, R. 1977. Aggression as a social mechanism in the creek chub ( Semotilus atromaculatus ). Copeia , 1977: 393-397.

Moshenko, R., J. Gee. 1973. Diet, time and place of spawning, and environments occupied by creek chub ( Semotilus atromaculatus ) in the Mink River, Manitoba. Journal of the Fisheries Board of Canada , 30.3: 357-362.

Moshenko, R. 1972. Ecology of the northern creek chub, Semotilus atromaculatus (Mitchill) in the Mink River, Manitoba . Winnipeg, Manitoba: The University of Manitoba.

Nagrodski, A., C. Suski, S. Cooke. 2013. Health, condition, and survival of creek chub ( Semotilus atromaculatus ) across a gradient of stream habitat quality following an experimental cortisol challenge. Hydrobiologia , 702.1: 283-293.

Pflieger, W. 1997. The Fishes of Missouri . Jefferson City, MO: Missouri Department of Conservation.

Quist, M., M. Bower, W. Hubert. 2006. Summer food habits and trophic overlap of round tail chub and creek cub in Muddy Creek, Wyoming. The Southwestern Naturalist , 51/1: 22-27.

Simon, T. 2011. Fishes of Indiana . Bloomington, IN: Indiana University Press.

Stauffer, J. 2007. Fishes of West Virginia . The Pennsylvania Sate University: Academy of Natural Sciences.

U.S. Bureaus of Fisheries. Methods of studying the habits of fishes, with an account of breeding habits of the horned dace. 28. Washington, D.C.: 1113-1136. 1908.