Melanogrammus aeglefinus

Last updated: May 27, 2024
Verified by: AZ Animals Staff
NORTHERN IMAGERY/Shutterstock.com

The haddock is very popular in both recreational and commercial fishing


Haddock Scientific Classification

Scientific Name
Melanogrammus aeglefinus

Read our Complete Guide to Classification of Animals.

Haddock Conservation Status

Haddock Locations

Haddock Locations

Haddock Facts

Worms, sea stars, urchins, sand dollars, mollusks, crustaceans, fish, and eggs
Group Behavior
  • School
Fun Fact
The haddock is very popular in both recreational and commercial fishing
Biggest Threat
Most Distinctive Feature
The black “thumbprint” on the sides of the body
Gestation Period
1 to 3 weeks
Skates, dogfish, cods, halibuts, and seals
Ray-in fish
Common Name
Number Of Species
North Atlantic Ocean

Haddock Physical Characteristics

  • Red
  • Black
  • Purple
Skin Type
10 years or more
2-40 pounds
30 cm-91 cm (1 ft-3 ft)

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The haddock is a deep-sea marine fish, native to the North Atlantic.

Haddock is an immensely popular food around the world, perhaps nowhere more so than the United Kingdom, where it’s practically a staple in some local dishes. This fish is closely related to cod, another popular dish. With a firm and slightly sweet taste, it is commonly fried, baked, and smoked.

3 Incredible Haddock Facts!

  • It is adapted to life in deep, cold waters at around 35 to 50 degrees Fahrenheit.
  • Haddocks swim together in large schools for protection.
  • Despite being a deep sea fish, this fish spends the early part of its life near the surface. Its diet and behavioral habits change with age.

Haddock Classification and Scientific Name

The scientific name of the haddock is Melanogrammus aeglefinus. Melanogrammus basically means black line in Greek. Aeglefinus comes from the French word for the haddock, églefin. As a type of ray-fin fish, it is a member of the true cod family and the only living member of its genus.

Haddock Appearance

The haddock is a medium-sized fish, measuring anywhere between 1 and 3 feet in length and about 7 pounds (though the largest one ever caught was an immense 40 pounds). It is most easily identified by the black or purplish line running along the back and the distinctive marking on each side of the body. This marking is sometimes referred to as the “Devil’s thumbprint,” and it’s quite conspicuous against the white or silvery body. The haddock is also characterized by three dorsal fins along the back, two anal fins along the bottom, and a small barbel on the chin, the purpose of which is probably to sense its surrounding environment.

Similar to the cod, haddock is often caught for culinary purposes.

Cod vs. Haddock

There are actually several species of cod, versus only one species of haddock. The most closely related species to the haddock is probably the Atlantic cod. Both of them have a similar body shape, a similar arrangement of fins, and the same chin barbel. But the main difference is that the cod tends to be much larger, sometimes more than twice as large, and lacks the same markings.

Distribution, Population, and Habitat

This fish can be found on either side of the North Atlantic, usually swimming at depths of 300 to 700 feet, though sometimes as deep as 1,500 feet. The largest stocks in United States waters are located in the Gulf of Maine and Georges Bank (off the coast of New England). They are currently classified by the IUCN Red List as a vulnerable species, but this assessment may be out of date because its status hasn’t been properly evaluated since 1996.

The NOAA (National Oceanic and Atmospheric Administration) keeps careful track of population levels in the Atlantic every year. They estimate that population levels remain above average, thanks to the careful management of existing stocks. This represents an improvement from population levels in the latter half of the 20th century when the haddock stocks were stressed. The United States has also put in place regulations designed to minimize accidental bycatch.

Predators and Prey

This fish is a carnivorous predator. It spends much of its time searching around on the ocean floor for slow-moving invertebrates and smaller fish. It can move relatively quickly to evade potential predators.

What eats the haddock?

Juveniles are preyed upon by skates, spiny dogfish, cod, halibuts, and other groundfish. Adults are also preyed upon by grey seals.

What does the haddock eat?

The haddock feeds on worms, sea stars, sea urchins, sand dollars, mollusks, crustaceans, and occasionally smaller fish and eggs.

Reproduction and Lifespan

Haddocks typically spawn between January and June, at least in American waters, when the schools come together to breed. Egg production depends on the size of the female. Every breeding season, the average female produces about 850,000 eggs, and the larger females can produce around three million. The female releases her eggs in large clutches near the ocean floor, where the male will then fertilize them. The eggs then rise to the surface along the water column and drift along the ocean currents for about 15 days.

Newly hatched haddocks spend the first few months of their lives near the coast, feeding on small crustaceans called copepods. After reaching about 3 inches in length, the haddock travel back down to the depths and transition to an adult diet. By the end of the first year, the haddock has reached about a foot in size, but it may take anywhere up to four years to achieve full sexual maturity and begin reproducing. The typical lifespan of the haddock is 10 or more years. Many of the fish are caught between the ages of three and seven after they’ve had an adequate opportunity to reproduce. Obviously, given the number of eggs produced, haddock suffer massive attrition before most of them ever reach adulthood.

Fishing and Cooking

The haddock is one of the most popular saltwater marine fishes in the United States and northern Europe. They are harvested all year round using long lines, gill nets, and rod and reel lines to minimize the impact on the surrounding habitats. Trawls are also used with some restrictions. In 2019 alone, commercial fishing yielded more than 19 million pounds of haddock, valued at nearly $19 million. Recreational fishers caught an additional 1.8 million pounds.

The flesh of the haddock is very similar to cod: white, firm, and moist. The flesh is so similar, in fact, that they’re sometimes used interchangeably with each other, although the haddock has a slightly sweeter taste. In the United Kingdom, both haddock and cod are popular components of fish and chips recipes, in which the fish is battered and fried in oil. Finnan haddie is the name of cold-smoked haddock originating from the northeast of Scotland. Other popular recipes include baked haddock covered in bread crumbs.

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Haddock FAQs (Frequently Asked Questions) 

What is haddock?

The haddock is a medium-sized saltwater ray-fin fish. It is a member of the true cod family. As a carnivore, most of its prey consists of slow-moving invertebrates along the ocean floor.

Where are haddock found?

Haddocks are found on both sides of the North Atlantic, nestled within gulfs, banks, and bays. Adults spend most of their time near the ocean floor.

Is haddock healthy?

Haddock is high in protein, Vitamin B12, omega-3 fatty acids, potassium, and a few other vital nutrients. The mercury content is fairly low compared to many marine saltwater fish (0.055 parts per million). Most healthy adults probably don’t need to limit the number of servings they consume per week.

How do you cook haddock?

Some of the most common recipes include fried haddock (as in fish and chips) or baked haddock with bread crumbs.

What are the diferences between haddock and halibut?

Haddock and halibut differ in appearance, size, diet, distribution, predators, reproduction, and lifespan.

What are the diferences between haddocks and Alaska pollocks?

Haddocks and Alaska pollocks differ in size, appearance, habitat, range, taxonomy, and conservation status.

What are the differences between haddocks and flounders?

The differences between haddocks and flounders are appearance, size, diet, distribution, predators, reproduction, and lifespan.

What are the differences between haddocks and salmon?

The differences between haddocks and salmon include appearance, size, diet, habitat, reproduction, and lifespan.

What are the differences between pollocks and haddocks?

The differences between pollocks and haddocks include appearance, size, diet, distribution, reproduction, and lifespan.

What are the differences between tilapias and haddocks?

The differences between tilapias and haddocks include appearance, size, diet, distribution, reproduction, and lifespan.

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  1. NOAA Fisheries / Accessed August 2, 2021
  2. Mass.gov / Accessed August 2, 2021