The haddock is a fish. 

The haddock is a fish in the sea. 

The haddock is a saltwater fish. 

Haddock have a long body shape. Their backs are dark grey or black. Their bellies are a silvery white. A dark line runs along their side. They also have a black spot. This spot looks like a thumbprint. Some people call it the "Devil's thumbprint."
These fish like to live near the ocean floor. This is called being demersal. They like to swim over sand, rock, or shells. Haddock eat many things. Adults eat worms and sea urchins. They also eat small fish.
Haddock are very popular to eat. People buy them fresh or frozen. Some people like them smoked. You might see them in fish and chips. In the UK, they are a very common food. Scientists study how many fish are caught each year. This helps keep the fish populations safe.
The haddock is a saltwater fish found in the North Atlantic Ocean. 

This fish has a very specific look that helps people identify it. Its body is long and tapers at the ends. The top of the fish is dark grey or black. The bottom part is a dull silvery white. A dark line called a lateral line curves along its side.
Haddock live near the bottom of the ocean. Scientists call these bottom-dwelling fish demersal. They like to swim over sand, gravel, rock, or shells. They prefer water temperatures between 2 and 11 degrees Celsius. 
People have studied these fish for a long time. A scientist named Carolus Linnaeus first described the haddock in 1758. Later, in 1862, Theodore Nicholas Gill created the genus name. Haddock are caught in huge amounts every year. In the eastern Atlantic, landings were between 200,000 and 350,000 tonnes from 1980 to 2017. 
You might recognize haddock if you have ever eaten fish and chips. It is one of the most popular fish for that meal. Haddock also play a big role in the ocean food web. Small baby fish eat tiny creatures called copepods. As they grow up, they eat bigger things like sea urchins and worms. 
The haddock, known scientifically as Melanogrammus aeglefinus, is a saltwater fish. It belongs to the family Gadidae, which contains the true cods. This fish is unique because it is the only species in its genus, Melanogrammus. 

Physically, the haddock has an elongated, tapering body shape. This shape is very common among members of the cod family. Its mouth is relatively small and does not reach below the eye. The face has a straight lower profile and a slightly rounded upper profile. This creates a snout that looks like a wedge. The upper jaw projects further than the lower jaw, even more so than in the Atlantic cod. A small barbel, which is a fleshy whisker, sits on its chin.
The haddock possesses several specific fins that help it move. It has three dorsal fins on its back. The first is triangular and contains 14 to 17 fin rays. The second has 20 to 24 rays, and the third has 19 to 22 rays. There are also two anal fins on the underside. The first anal fin has 21 to 25 rays, while the second has 20 to 24 rays. All these fins are separated from one another. The pelvic fins are small and feature an elongated first fin ray.
Coloration is a key way to identify a haddock. The upper body ranges from dark grey-brown to nearly black. The lower body is a dull silvery white. A distinctive black lateral line curves over the pectoral fins. A very famous feature is an oval black blotch called a "thumbprint." Some people call this the "Devil's thumbprint." This mark sits between the lateral line and the pectoral fin. The genus name Melanogrammus comes from the Greek words "melanos," meaning black, and "gramma," meaning letter or signal.
Haddock are demersal, meaning they live near the ocean floor. They typically live at depths between 20 and 200 meters. They are most often found at 50 to 150 meters. These fish prefer substrates like rock, sand, gravel, or shells. They thrive in water temperatures between 2 and 11 degrees Celsius. 
The life cycle of a haddock involves many stages. They reach sexual maturity at 4 years for males and 5 years for females. However, the North Sea population matures faster, at 2 years for males and 3 years for females. Females produce many eggs, a measure called fecundity. A fish of 50 centimeters long may bear 55,000 eggs. A much larger fish of 100 centimeters can produce 1,841,000 eggs. The eggs are pelagic, meaning they float in the open water. They have a diameter of 1.2 millimeters and hatch in one to three weeks. Once they undergo metamorphosis, the larvae remain pelagic until they reach 10 centimeters. At that point, they settle into a demersal habit on the bottom.
Dietary habits change as the fish grows. Larval haddock eat tiny creatures like copepods and ostracods. As they grow, they eat larger prey like amphipods and even invertebrate eggs. Once they become demersal, they switch to benthic prey. This includes bottom-dwelling animals like sea urchins, brittlestars, bivalves, and worms. They also eat smaller fish like capelin or sandeels. Haddock are part of a complex food web. Juvenile haddock are eaten by larger fish, while seals prey on the larger adults. 
Humans have fished haddock for a very long time. Carolus Linnaeus first described the species in 1758. In 1862, Theodore Nicholas Gill created the genus Melanogrammus. Today, haddock is a major commercial resource. In the eastern Atlantic, landings reached between 200,000 and 350,000 tonnes between 1980 and 2017. 
🖼️ Images & Media (4)
More to explore
✨ What else?
Related topics you might enjoy
What is Nepedia?
A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.