The burbot is the only freshwater fish in the cod family

Nature · Published 3 October 2026 Swipe more like this →

In short: While most cod species roam the open ocean, the burbot thrives in cold rivers and lakes across the Northern Hemisphere. This elusive, bottom-dwelling predator is a biological outlier, uniquely adapted to survive and breed in frigid, ice-covered waters where other fish struggle to persist.

The burbot (Lota lota) occupies a singular niche as the only freshwater member of the order Gadiformes. Belonging to the family Lotidae, it shares a lineage with marine relatives like the common ling and cusk. Its physical appearance is often described as a hybrid between an eel and a catfish, characterized by an elongated, mottled body and a distinct single chin barbel—a feature that gives the fish its name, derived from the Latin word for beard.

Unlike most freshwater species that spawn in warmer months, the burbot is a winter specialist. It requires frigid temperatures to breed, typically spawning between December and March. During this window, they often gather in 'spawning balls' beneath the ice, where multiple males surround one or two females to release eggs and sperm into the water column. These broadcast spawners do not build nests; instead, their eggs drift until settling into substrate voids. Fecundity is remarkably high, with a single female capable of producing over three million eggs depending on her size.

Burbot are highly resilient, inhabiting cold waters across Europe, Asia, and North America. They are capable of descending to depths of 700 metres and are known to be slow-growing, long-lived creatures that can exceed 20 years of age. While they are common in many regions, their status in the United Kingdom is precarious, with the species possibly extinct there since the last confirmed capture in 1970. Their reliance on cold, stable environments makes them a fascinating subject for understanding how specialized vertebrates navigate extreme, ice-bound ecosystems.

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