Ohio Lamprey

The Ohio lamprey (Ichthyomyzon bdellium) is a parasitic jawless fish found in medium to large river systems of the eastern and central United States, including the Ohio, Tennessee, and Cumberland River drainages. It belongs to the genus Ichthyomyzon, a group of lampreys endemic to North America, and is one of several closely related species that can be difficult to distinguish without close examination. As an adult, it attaches to other fish using a circular toothed sucking disc and feeds on their blood and body fluids for a period before detaching. Like other lampreys, it spends the majority of its life cycle as a burrowing larva before undergoing metamorphosis into the free-swimming, feeding adult form. It remains entirely within freshwater throughout its life.

• Slender, scaleless, eel-like body, olive to grayish-brown in color
• Circular sucking-disc mouth armed with sharp, pointed horny teeth arranged in distinct rows
• Seven round gill openings positioned behind the head
• Continuous or barely notched dorsal fin set well back on the body
• Adult length typically 15-30 cm, intermediate among Ichthyomyzon species

Ohio lamprey can be difficult to separate from closely related Ichthyomyzon species such as the mountain brook lamprey without examining fine details of tooth pattern and dorsal fin shape, but its larger parasitic-adult size and well-developed dentition distinguish it from smaller, non-parasitic brook lampreys sharing its range.

Ohio lampreys live entirely within freshwater river systems of the eastern and central United States, primarily in the Ohio River basin and portions of the Tennessee and Cumberland drainages. Adults favor moderate to swift-flowing sections of medium to large rivers with clean gravel or rocky substrate, where they can find host fish and suitable spawning riffles. Larvae burrow into softer sand and silt deposits in slower backwater and pool areas of the same river systems, where they remain for several years. The species requires good water quality and unobstructed river connectivity, and populations can decline where waterways are dammed, channelized, or heavily silted.

Adult Ohio lampreys are parasitic, attaching to the sides of host fish with their toothed sucking disc and rasping through the skin to feed on blood and body fluids over a period of days before releasing their host, which often survives the encounter. After a parasitic feeding phase lasting roughly a year, adults migrate to gravel riffles to spawn, building a shallow nest by moving stones with their mouths, and die soon after spawning. Larvae are filter feeders, burrowing into fine sediment and straining algae, detritus, and microorganisms from the water for several years before metamorphosing. As parasites and detritivores, Ohio lampreys interact with both fish populations and organic nutrient cycling in their river habitat.