The Central Mudminnow (Umbra limi) was described in 1840 by Ohio naturalist and politician Jared Potter Kirtland. Umbra meaning "phantom," describes the quick movements these fish can make; limi means "of the mud," coming from their preferred habitat. At first glance, the Central Mudminnow resembles a Bowfin but are cousins to the famous "sport fishes," Northern Pike and Muskellunge. The Mudminnow only reaches a maximum length of roughly 14 cm (5.5 inches). These fish are capable of surviving in water temperatures up to 37.7 C (100 F)!
Central Mudminnow from a wetland stream in northeastern IL.
Like their big cousins, these fish can occupy both lake and stream systems. Their preferred habitat is densely vegetated, slow-moving water that contains soft sediments (mud, sand, etc.). The Central Mudminnow uses the substrate as a hiding place by entering the substrate tail-first. This peculiar behavior was observed by J. P. Kirtland in 1838, when he noticed one buried in the mud while a swamp was being ditched (Rice and Zimmerman, 2019).
The primary forage is crustaceans and aquatic insects that reside in vegetation or near the bottom of their habitat. Like their larger cousins, adult Central Mudminnows are considered carnivorous, primarily during the winter months. While other species hug the bottom of lakes or streams in winter, the Mudminnow will energetically feed on smaller fish. They fall prey to various fishes like, Grass Pickerel or Channel Catfish to terrestrial animals such as herons and foxes.
Central Mudminnow from a tributary stream of the West Branch DuPage River, IL.
Spawning usually begins when the water temperatures reach roughly 13 C (55.4 F). Males will establish and defend their breeding territory within the vegetation. They work to attract females by developing a bright blue shine in the pelvic and anal fins. Females deposits adhesive eggs onto the stems and leaves of the aquatic vegetation. They will then guard the nest until all their eggs have hatched.
The image from FishMap shows the expansive range that the Central Mudminnow covers. Their native range extends across the Great Lakes region and down to northwest Tennessee. Grey watersheds show current findings, while red are their historic locations. Unfortunately, these fish have non-native occurrences in 17 states, being introduced to the system either via bait buckets or aquarium releases. They are tolerant to turbid waters and low oxygen levels. They possess a specially modified swim bladder that allows them to breathe air! While the Central Mudminnow is a species of "least concern," their primary habitats in wetlands, are continually under attack by development and will likely cause a decline in the future.
The best option to observe these pygmy pikes is to take a seine or dip net and find a nicely vegetated marsh, lake, or stream. Run the net through the vegetation while keeping in contact with the substrate and see what you can find! You can put them in an aquarium filled with floating or submerged plants and soft bottom, but make sure to have other fish with them. Central Mudminnows are considered a shoaling fish and do best when there are different species around. These little fish might be unknown to most, but they and their habitat deserve our attention and understanding. No matter how you choose to observe them, make sure you continually enjoy, protect, and enhance our freshwater areas!
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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