Currently, central mudminnows are listed as state threatened in Kentucky; state endangered in South Dakota, and are a candidate species in Pennsylvania. They are protected or of special concern in Missouri and North Dakota (Tomelleri and Eberle 1990).
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
Central mudminnows are preyed on by grass pickerel, chain pickerel, northern pike, sunfishes, catfishes and sculpins (Peckham and Dineen 1957; Becker 1983). Their chief predator are mottled sculpin (Cottus bairdii) according to Peckham and Dineen (1957). The same study noted that one 111 mm male mottled sculpin stomach contained a 72 mm female central mudminnow. Terrestrial predators include herons, muskrats and foxes according to Becker (1983). A Wisconsin-based study that focused on Perca-Umbra assemblages suggested that size-dependent predator-prey interactions between perch and central mudminnows was a driving mechanism in population organization (Tonn and Paszkowski 1986). This same study noted that U. limi could briefly override this relationship during winterkill events via facultative breathing behaviors.
Known Predators:
Anti-predator Adaptations: cryptic
Central mudminnow adult sizes range between 50 to 115 mm (Tomelleri and Eberle 1990). The average adult size is 60 mm (Becker 1983). Young-of-year average length is 29.5 mm and yearling average length is 41.5 mm (Applegate 1943). Schilling et al. (2006) recorded a maximum standard size of 140 mm. The body has a nearly round cross section and robust appearance. The snout is stubby with a terminal mouth. The premaxillary and lower jaws and roof of mouth all have small villiform teeth. The dorsal fin is set back towards the posterior half. The caudal fin is convexly rounded. The anal fin is larger than the pelvic and longer in males, almost reaching the caudal fin. Males also develop a blue-green coloration on the anal fin during spawning season. There is no gross sexual dimorphism in length (Applegate 1943). Meristic features include 13 to 15 short gill rakers, 4 to 5 branchiostegal rays, 13 to 15 dorsal fin rays, 7 to 9 anal fin rays, 14 to 16 pectoral fin rays, and 6 to 7 pelvic fin rays (Becker 1983).
Overall coloration is dark olive-green to brown-black with 14 vertical dark brown bars along the lateral surfaces. The scales are large and cycloid. The top of the head, cheeks, and opercles are scaled. There is a prominent, vertical, dusky bar at the caudal base. The ventral surface is yellow to white. Central mudminnows use a diodontiform swimming pattern with undulation of median or pectoral fins. Central mudminnows can be mistaken for banded killifish (Fundulus diaphanus). Differentiation between the two species can be made by examining the mouth; Fundulus diaphanus has a supraterminal mouth whereas U. limi has a terminal mouth.
Range length: 50 to 115 mm.
Average length: 60 mm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: sexes colored or patterned differently; male more colorful; sexes shaped differently
It is thought that central mudminnows live for approximately 7 to 9 years. Age is usually determined by otoliths and opercula since the scales do not contain annuli (Becker 1983; Applegate 1943).
Typical lifespan
Status: wild: 7 to 9 years.
Central mudminnows are resilient and thrive in waters with dense vegetation, low dissolved oxygen levels, minimal flow, and thick layers of organic substrate (Schilling et al. 2006; Becker 1983; Peckham and Dineen 1957). Their name is derived from the Latin umbra meaning shadow or phantom and limi meaning mud. They are also known as mudfish, mudpuppy, or dogfish (Tomelleri and Eberle 1990). They inhabit both lotic and lentic habitats, providing that the waters are still or slow moving and there is dense cover available (Chilton et al. 1984). They are most commonly encountered in water less than five meters deep (Becker 1983). In Wisconsin, this species is commonly found among cattail, waterweed, eel grass, bulrush, yellow water lily, water buttercup, and filamentous algae (Becker 1983). They are a predominantly benthic fish, provided the stream bed or lake bottom is within the preferred depth. During periods of high flow, central mudminnows move from their normal habitats and venture into the flooded areas along the banks to avoid strong water currents (Peckham and Dineen 1954). They can endure hypoxic conditions for short periods of time via facultative air breathing (Tomelleri and Eberle 1990; Schilling et al. 2006; Rahel and Nutzman 1994; Klinger et al. 1982; Chilton et al. 1984; Tonn and Paszkowski 1986). Central mudminnows may be considered habitat specialists based on their adaptation for living in areas with dense macrophyte communities (Peckham and Dineen 1954).
Range depth: 5 (high) m.
Habitat Regions: temperate ; freshwater
Aquatic Biomes: benthic ; lakes and ponds; rivers and streams; temporary pools
Wetlands: marsh ; swamp ; bog
Other Habitat Features: riparian
Central mudminnows are native to the Nearctic, found in both Canada and the United States. Their native range includes the Great Lakes, Hudson Bay, the St. Lawrence, Red, and Mississippi River basins from Quebec to Manitoba and south to central Ohio, Tennessee, and northeastern Arkansas. There are isolated populations in the Missouri River basin in South Dakota and Iowa. Montana, Oklahoma, and Texas have had reports of isolated, non-native occurrences. Reports of introduced central mudminnow populations or individuals in eastern North America, including Connecticut, Massachusetts, and Maine have been made in the last twenty years.
Biogeographic Regions: nearctic (Introduced , Native )
Central mudminnows are primarily bottom feeders (Becker 1983) and generally carnivorous (Peckham and Dineen 1957). Central mudminnow diet includes small crustaceans, amphipods, isopod crustaceans, crayfish, chironomid larvae, culicid larvae and pupae, dixid larvae, long-legged fly larvae, crane flies, mayflies, earthworms and a variety of small fishes. The potential for cannibalism was briefly discussed by Peckham and Dineen (1957), but the presence of mudminnow scales in sampled mudminnow stomachs could have been accidental ingestion.
Juvenile winter diet of Age 0 included copepods and larval chironomids (Chilton et al. 1984). Young-of-year also feed on ostracods and cladocerans (Becker 1983). Peckham and Dineen (1957) noted that young fish (19 mm) fed on newly hatched snails, while Chilton et al (1984) found Age 1 consumed both chironomids and fishes. Small central mudminnows were not found foraging in hypoxic waters that larger central mudminnows use and might be attributed to their inefficiency in capturing the primary prey item, Chaoborus larvae, found in those waters (Rahel and Nutzman 1994). Chilton et al. (1984) detected piscivory only in female central mudminnows. They typically capture prey head first but as the temperature drops to around 1.1 ⁰C, capture is side-on and then reoriented to head first substantially increasing handling time to ~10 minutes.
Animal Foods: fish; eggs; terrestrial non-insect arthropods; terrestrial worms; aquatic or marine worms; aquatic crustaceans; zooplankton
Plant Foods: algae; phytoplankton
Primary Diet: carnivore (Insectivore )
Since central mudminnows are able to survive in relatively hypoxic conditions when many other species are killed, they play an important role in their ecosystems (Tonn and Paszkowski 1986). Their preference for, and success in, heavily vegetated habitats also makes them a specialist (Peckham and Dineen 1954). They are an important prey item for many species. In the Umbra-Perca assemblages studied by Tonn and Paszkowski (1986), size-dependent predator-prey interaction between the two species (Umbra limi and Perca flavescens) was a major organizational mechanism of the assemblage.
Fishermen are familiar with central mudminnows as hardy bait fish. Their facultative air-breathing and overall tolerance of extreme environmental conditions make them an excellent bucket fish (Schilling et al. 2006). Long-lived, attractive, and easy to care for, U. limi is an interesting fish in aquaria. Individuals can easily be trained to take food pieces from people (Becker 1983). Jenkins and Miller (2006) note that they are well suited for laboratory study, most likely for the reasons listed above. They also mention that few studies have been conducted on the behavior of central mudminnows.
There are no known adverse effects of Umbra limi on humans.
Fry are transparent and approximately 5 mm upon hatching (Peckham and Dineen 1957). Fry become pigmented and dark on their 16th day after hatching. Until young reach 25 mm they have a notochord lobe above the developing caudal fin (Becker 1983). When young reach 30 mm they move from flooded margins and pools back into the main stream or preferred adult lentic habitats. Becker (1983) notes the timing of length attained in southern Wisconsin young-of-year as late June - 28 mm, mid-July - 35 mm, late July - 39 mm, mid-August - 43 mm, and 55 mm by October. Applegate (1943) noted that, with increasing size and age, the relative abundance of males decreases and the larger and older fish were mainly female.
Development - Life Cycle: indeterminate growth
Jenkins and Miller (2006) demonstrated that central mudminnows use visual clues to compare the size of shoals. Although this study did not include laboratory tests to test olfactory or tactile cues that may be used in their natural habitat, it was noted that these sensory systems play a major role in shoaling decisions. These findings are not direct evidence of communication but reflect the use of visual, olfactory, and tactile cues in social behaviors such as shoaling. Further study of communication in this species may be warranted.
Communication Channels: visual ; tactile ; chemical
Perception Channels: visual ; tactile ; chemical
Additional study of reproductive behaviors may be warranted, as there is little information on mating behavior.
Spawning is most likely prompted by warming water temperatures and flooding in spring (Becker 1983; Peckham and Dineen 1957). Preferred water temperature for spawning is 12.8⁰C but can occur at up to 15.3⁰C (Becker 1983). Many references note spring migration of central mudminnows into flooded areas. Spawning habitat is preferably flooded stream margins and pools with slow or no flow (Tomelleri and Eberle 1990). Eggs are demersal and adhesive. Females affix eggs individually directly to vegetation (Peckham and Dineen 1957). Fecundity is 425 to 450 eggs per female on average. Eggs are yellow or orange and measure about 1.6 mm in diameter. Within individual ovaries all eggs were the same size before spawning season and ripen at the same time, indicating a short spawning season (Peckham and Dineen 1957). There is some egg guarding behavior by the female (Becker 1983).
Breeding interval: Central mudminnows are thought to breed once a year.
Breeding season: Spawning is most likely prompted by warming water temperatures and flooding in spring.
Range number of offspring: 425 to 450.
Average number of offspring: 432.
Average gestation period: 6 days.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous
There is some egg guarding behavior by the female (Becker 1983).
Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Protecting: Female)
The central mudminnow (Umbra limi) is a small fish in the family Umbridae of the order Esociformes. It is found in central and eastern North America in productive waters.[2] It is fairly tolerant of low oxygen concentrations and, as a result, it is sometimes the only, or one of a very few, fish species present in waters susceptible to winter or summer kill.
The central mudminnow lives in slow-moving water around ponds, lakes, and streams in central North America, and ranges in length from 51–102 mm.[3] It burrows tail-first in mud and can tolerate low oxygen levels, allowing it to live in waterways unavailable to other fishes. Its coloration matches this habitat, being brownish above with mottled sides and a pale belly.[4] It is eaten by many species of fish such as grass pickerel, sunfishes, northern pike, and catfishes; it is also preyed upon by birds, foxes, and snakes when caught out of water.[5] According to Paszkowski and Tonn, mudminnows perform better in environments with other fish species than in environments with just mudminnows, because the "interspecific interactions override a similar contribution for the mudminnow, which is regarded as a fugitive species".[6] Central mudminnows are known to eat a large variety of zooplankton and benthic and epiphytic macroinvertebrates. Adults are also known to feed energetically in the winter months on littoral fish.[7] One experiment conducted by Colgan and Silburt resulted in mudminnows typically feeding more on benthic than planktonic resources, with zooplankton making up only 0.7% out of 511 items found in the stomach.[8] This mudminnow uses a modified gas bladder to breathe air pockets trapped between the ice and water during the winter to feed and stay active.[9]
Umbra limi is a widely distributed species that inhabits many freshwater systems such as lakes, streams, and wetlands near the littoral zone, or near the shore, and around dense cover in central North America west of the Appalachian Mountains, including the St. Lawrence River, Great Lakes, Hudson Bay (Red River, and the Mississippi River basins from Quebec to Manitoba and south to central Ohio, western Tennessee, and northeastern Arkansas.[10] The central mudminnow has also been introduced into many of the tributaries in Connecticut and Massachusetts. Their habitats being marshy lands and rivers are under attack by human development and contact constantly and is likely causing a decline in their populations.
The central mudminnow is carnivorous and typically feeds in the benthic area of freshwater habitats. According to Colgan and Silburt, it prefers amphipods, coleopterans, and anisopterans while avoiding zooplankton and other planktonic species. In a study by Colgan and Silburt, they found that an average of only 0.9% of the contents of dissected stomachs of U. limi contained zooplankton. Chironoids and gastropods, when taken from the dissection, had a combined volume of about 60%, which proves that the mudminnow feeds mainly in benthic areas.
This fish seems to prefer water with low dissolved oxygen levels, warmer temperatures, and low flow.[10] It is able to live in hypoxic conditions because of its ability to breathe air.[11] This species is also known to feed in the winter in temperatures as low as 1.1 °C.[11] According to Jenkins and Miller, some animals that feed on the mudminnow are the grass pickerel, sunfishes, northern pike, and catfishes; it is also preyed upon by birds, foxes, and snakes when caught out of water. This mudminnow is known to bury itself in the mud or sand to avoid capture in some situations. Also, Jenkins and Miller found that the mudminnow is a shoaling fish; they prefer to be with other mudminnows rather than by themselves. This shoaling mechanism seems reduce their predation risk.[5]
The central mudminnow tends to spawn in mid-April in temperatures of 13 °C with the higher temperature stimulating the spawning. Spawning can take place in shallow waters and produce up to 2,500 eggs in one season. The average age of the central mudminnow is three, while they can reach ages of five or six. Females are typically larger than males when compared around age two. The egg stage is generally six days and then they enter the larval stage of development.[7]
The central mudminnow (Umbra limi) is a small fish in the family Umbridae of the order Esociformes. It is found in central and eastern North America in productive waters. It is fairly tolerant of low oxygen concentrations and, as a result, it is sometimes the only, or one of a very few, fish species present in waters susceptible to winter or summer kill.
