Eels first appeared more than 65 million years ago and they continue to thrive to this day. There are over 800 species of eel worldwide and most populations show no signs of decay. Whether they live in fresh or salt water, these ray fins find a way to dominate their territory. Half a fish, half a snake, and a mouth full of razor sharp teeth, it is not difficult to imagine these mysterious creatures in the form of powerful sea monsters.
Despite their fearsome appearance, eels play a crucial role in marine ecosystems. With few natural predators, these nocturnal hunters prey on everything from fish to crustaceans and other eels. Some species live up to 20 years and can grow to enormous sizes. Although they come in a wide variety of shapes and sizes, from tiny pygmy eels to giant moray eels, they are the largest species that most often grabs our attention. These specimens are nicknamed the “Sea Devil” eel due to their gigantic size.
To determine which type of blackhead is the largest, you must compare its length and weight, with weight being the most important factor. Although some species, such as electric eels and wolf eels, are called eels, they belong to different families of animals and are not true eels. Thus, despite their enormous size, they cannot be considered the largest eels. With that in mind, here is a list of the 10 biggest blackheads in the world.
# 10: South Konger
Southern conger eel (Conger verreauxi) is a member of the Congridae family. In their largest size, they reach 6.5 feet in length and weigh up to 11 pounds. Their elongated brownish-gray bodies are similar to the most common types of conger eels. They are often found in the waters off the southern coasts of Australia and New Zealand.
Southern algae are typically found in rocky reef areas up to 330 feet deep. As opportunistic nocturnal hunters, they eat everything from fish to crustaceans and even other eels. They are currently listed as the Least Concern species by the IUCN.
# 9: California moray

California moray (Gymnothorax mordax) got its name because it is the only species of moray eel that lives off the coast of California. They can grow up to 5 feet in length and weigh nearly 15 pounds in their most severe condition. They range in appearance from mottled brown to almost entirely green. While most moray eels live in temperate waters, California moray eels are one of the few subtropical representatives of this species.
If you want to see one in the wild, they usually occupy a rocky environment about 120 feet below sea level. Their diet is mostly fish, but they also eat lobster, shrimp, and octopus. Since they are not used commercially and do not have predators, they are classified as Least Concern by the IUCN.
# 8: American eel

American eel (Anguilla rostrata) migratory fish found off the east coast of North America. The largest specimens are about 4 feet long and weigh up to 17 pounds. They range in color from dark green with a brown tint to light gray with white belly. A layer of mucus covers their bodies, giving them a naked, slimy appearance.
American eels spend most of their life in fresh water and only go out into the ocean to spawn. Females can lay up to 4 million eggs at a time. Their diet includes crustaceans, insects and anything they can eat. Due to the loss of habitat caused by the construction of dams along the migration routes, their number has decreased significantly in recent years. As a result, the IUCN ranks them as endangered species.
# 7: Toothed moray eel

Also known as tiger moray or conger eel, toothy moray (Enchelikor anatina) is one of the most terrifying of this species. It gets its name from the row of large glass teeth lining its mouth. They can grow up to 4 feet long and weigh up to 30 pounds. Their appearance is easily distinguished by their bright yellow-orange and brown coloration.
They can be found in the warmer regions of the Atlantic Ocean, including the Mediterranean Sea, the Canary Islands, and Madeira. Fangtooths live and hunt in the rocky crevices of the seabed. They mainly feed on crustaceans, cephalopods and bottom fish. The IUCN classifies the fanged moray eel as the least dangerous species.
# 6: Slender Giant Moray
Slender giant moray eel (Strfidon Satet) is the longest eel in the world. Even among eels known for their elongated bodies, the slender giant moray eels put other species to shame. The largest specimen ever found was an incredible 13 feet long. While their weight data varies according to their size, they can reach a maximum weight of around 40 pounds. They are usually brownish-gray, although their coloration tends to fade on the belly.
Thin giant moray eels are found throughout the Indian and Pacific Oceans, from the Red Sea to the western Pacific. They like a messy environment in which they can blend in with their surroundings. River estuaries and bays are considered their favorite hunting grounds. Their diet includes fish, crustaceans and molluscs. The IUCN classifies giant moray eels as the species of least concern. However, no study has evaluated the condition of the slender giant moray eels.
# 5: gray conger
Also known as Antillean conger eel, gray conger eel (Conger esculentus) is another common member of the conger eel family. They get their name from their sleek gray color, although their bellies appear more white than gray. While most individuals are usually around 3 feet in length, they can reach 5.2 feet in length and weigh nearly 55 pounds.
Gray algae are found in tropical and subtropical marine environments. They are found throughout the western central Atlantic Ocean, especially around Cuba, Jamaica, and northern South America. Capable of living 1,300 feet deep, gray marine life inhabit coral reefs and rocky areas at the bottom of the ocean. Their main food source is fish, as well as other bottom-eating species. Despite a thriving fishing industry for the gray conger eel, the IUCN classifies them as the species of least concern.
# 4: Green moray

Green moray eel (Gymnothorax funeral) – one of the largest species of moray eels. Their name comes from the bright greenish yellow color that runs the length of their body. Although sometimes confused with yellow moray eels, green moray eels can be easily distinguished by their size alone. They can grow up to 8 feet long and weigh around 65 pounds.
Green moray eels live in the western Atlantic Ocean from New Jersey to Bermuda and off the coast of Brazil. They live up to 130 feet below sea level. Like most moray eels, they are nocturnal. They mainly feed on fish, crab, shrimp, octopus and squid. The IUCN classifies the green moray eel as the species of least concern.
# 3: Giant moray

Giant moray eel (Gymnothorax javanicus) the largest moray eel by body weight. While the slender giant moray may be the longest eel in the world, the giant moray is much heavier than its skinny cousin. In their largest size, they can reach 9.8 feet in length and weigh 66 pounds. Their brownish bodies are covered with large tan spots, and in adults, two leopard spots are visible behind their heads.
You can find giant moray eels throughout the Indian and Pacific Oceans, including the east coast of Africa, the Red Sea, Hawaii, Polynesia, Fiji, and Japan. They live in lagoons and along the edges of coral reefs. Their diet mainly consists of fish and crustaceans. They have few predators and will even co-hunt with other fish species, such as the roaming coral bass. Although they are usually not aggressive towards humans, they will attack if cornered or threatened. They are currently listed as the Least Concern species by the IUCN.
# 2: American Conger
Also known as dog eel, venomous eel and conger eel, American conger eel (Conger oceanicus) is one of the largest types of eels. While most individuals are slightly over 3 feet long, they can reach 6.5 feet in length and weigh 88 pounds. Their bodies are usually dark gray, although their bellies usually appear whitish.
American algae are found in the western Atlantic Ocean from Cape Cod to northeastern Florida. Although they migrate, they do not spend part of their life in fresh water, unlike some types of eels. You can find them in shallow and deep waters, although they prefer to live along the seabed. They feed mainly on fish, shellfish and crustaceans. Although they have no natural predators, there is a small fishing industry for American sea coal. As their population is large and plentiful, IUCN classifies them as the species of least concern.
# 1: European conger

European conger eel (Conger Konger) is the largest eel in the world. On average, adults reach about 5 feet in length and weigh nearly 159 pounds. However, one huge specimen was 9.8 feet long and weighed 350 pounds. Their bodies are not covered with scales, and although they usually appear gray, they can also be blackish. Due to their large size and aggressive nature, they sometimes pose a danger to divers.
European algae can be found in the eastern Atlantic Ocean around Norway and Iceland, in the Mediterranean and Black Sea. Although sightings usually occur 0-1500 feet below the ocean surface, they can reach depths up to 10,000 feet below sea level when migrating to spawning grounds. They live in rocky outcrops called eels, and sometimes together with other eels. Their diet consists of fish, octopus, squid and crustaceans. Due to their widespread distribution and abundance, IUCN classifies them as of the Least Concern.