From deep-sea giants to the humble dinner plate, meet the versatile Gadiformes order.

Nature · Published 3 October 2026 Swipe more like this →

In short: The Gadiformes order includes some of the world's most commercially significant fish, from the iconic Atlantic cod to the haddock. While these ray-finned creatures primarily dominate temperate and cold marine environments, their diversity spans from tiny 7-centimeter codlets to massive 2-meter predators, revealing a complex evolutionary history.

The Gadiformes order, sometimes referred to as Anacanthini, represents a diverse group of ray-finned fish. Their physical architecture is distinct, characterized by spineless fins and pelvic fins positioned either in front of or directly below the pectoral fins. As physoclists, these fish lack a pneumatic duct connecting their swim bladders, a physiological trait that influences their buoyancy and depth management in the water column.

While the vast majority of Gadiformes are marine, their relationship with freshwater is nuanced. Most species are restricted to temperate or colder oceans, with tropical varieties typically confined to the deep sea. Only the burbot (Lota lota) is considered a true freshwater fish. Other species, such as the Pacific tomcod, may venture into brackish estuaries, though they do not breed there. Conversely, specific landlocked populations of Atlantic tomcod have adapted to complete their entire life cycle within freshwater environments.

The fossil record provides a glimpse into the ancient origins of this group. The earliest known specimens include Palaeogadus weltoni, discovered in the Maastrichtian of the United States, and the informally named Protocodus from the Early Paleocene of Greenland. Today, the order is categorized into numerous families, including Gadidae, which contains the commercially prized haddock. The haddock itself is a notable bottom-dwelling carnivore, identifiable by its dark lateral line and a signature dark spot on each shoulder, reaching sizes of up to 90 centimeters.

The economic importance of this order cannot be overstated, as it provides a foundation for global fisheries. From the deep-sea rattails to the familiar codlings and hakes, the diversity within Gadiformes highlights a successful evolutionary strategy. Whether they are swimming in the frigid North Atlantic or lurking in the deep ocean, these fish remain a cornerstone of marine ecosystems and human diets alike.

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