Central Mudminnow

Umbra limi is a fascinating and ecologically unique small fish native to the weedy, silty, slow-moving and often oxygen-depleted waters of the upper Mississippi Basin and Great Lakes region. It is a member of the ancient family Umbridae and is capable of surviving conditions that would kill virtually any other freshwater fish — including near-total deoxygenation and even brief periods frozen in ice under leaf litter. It accomplishes this through facultative air breathing, gulping air from the surface when dissolved oxygen is critically low.

In the aquarium, Central Mudminnows are best maintained in cool, heavily planted tanks with a deep layer of fine substrate into which they occasionally partially burrow. They appreciate slow water movement and plenty of vegetation for cover and hunting. Despite their survival abilities, they thrive best in well-maintained, cool, clean water.

They feed on aquatic invertebrates and small fish and are best kept as a species group or with similarly cool-adapted, peaceful tank companions. Their remarkable survival adaptations, secretive behaviour, and interesting predatory posture make them a compelling specialist aquarium subject.

Water: 5–22 °C, pH 5.5–8.0, soft to moderately hard; tolerates low oxygen — still needs adequate filtration. Tank: 80 L minimum; deep fine substrate, dense vegetation, slow flow; cool temperatures. Feeding: Live/frozen small invertebrates, worms, Daphnia; small sinking pellets accepted with training. Breeding: Deposits eggs in vegetation or substrate; guarded by female; achievable in species tanks. Compatibility: Semi-aggressive; may consume very small fish — keep with similarly sized cool-water species.