CATDOLL : CATDOLL: Is an eel a fish?

Is eel a fish? Absolutely! Now let’s learn more about eels!

Scientific name: The common Japanese white eel, its scientific name is Auguilla japonica, and its English name is Japanese eel.

Classification status: In taxonomy, fish are divided into two classes, namely Osteichthyes and Chondrichthyes. Fish belonging to the Osteichthyes have a hard internal skeleton; eels belong to the Osteichthyes, Anguilla, Anguilla, and Anguilla families.

Living habits: Eels are peripheral freshwater fish that are highly adaptable to seawater and can also live in freshwater. They usually live in rivers, lakes, ponds, swamps or estuaries, hiding in stone banks or earth holes during the day and coming out to look for food at night. They are nocturnal fish.

Body shape: The eel's body is slender like a snake, belonging to the long ribbon type, also called eel type.

Body color: The body color of eels varies with their habitats. Eels of different ages also have different body colors. Young eels are yellowish green, and once they reach the reproductive period, their color turns silver-gray. Female eels of the same age are lighter in color than male eels. Artificially farmed eels come in dark green, brown, and dark black colors, with blue being the most popular among consumers.

Size: Wild eels are about 60-90 cm long and weigh about one kilogram. They can be up to 130 cm long and weigh about five kilograms. However, the Japanese white eels we usually eat are mostly farmed adult eels, usually about 40-50 cm long and weighing about 150-500 grams, which means six eels weigh one kilogram to two eels weigh one kilogram.

Movement method: The eel's swimming method is a special serpentine type among fish's movement methods, also known as the eel type. Due to its long body and underdeveloped tail fin, it propels itself forward in an S-shaped curve when swimming, like a snake crawling, at a speed of about 2-4 kilometers per hour. Compared to the swordfish that can run 80 kilometers per hour, the eel is a slow eater.

Diet: Eels are carnivorous animals with small sickle-shaped teeth. They eat insects, small fish, fish eggs, small water birds, and even some humus in the water. Artificially bred eels eat artificial baits such as floating materials and powdered materials. The most special thing is that mature male and female eels do not eat anything during their journey back to the sea to lay eggs!

Lifespan: Wild eels can live for more than ten years, and the longest can live for fifty years; however, farmed eels are usually sold after one year. How do we know the age of an eel? We can look at the growth rings on the eel's scales, or we can take out the otoliths after the eel dies and do a biopsy. The otoliths in the eel's ears have rings like tree rings, one ring represents one year, and you can count them to know the true age of the eel.

Scales: Now that we have mentioned eel scales, you may be wondering: "Do eels have scales?" The answer is yes! Eel scales are very small and soft, hidden under the skin. If you don't look closely, you may not even notice them!

Gender: How to distinguish male and female eels? Here is a simple method! Generally speaking, female eels are larger than male eels of the same age and their body color is lighter.

Eel mucus: The eel's body surface often secretes mucus, which has a protective effect because the eel's skin can also absorb oxygen from the air. Therefore, after the eel leaves the water, as long as the mucus on the body surface is not dry, it can survive for a period of time without dying.

Downstream migration: The habit of eels to swim from freshwater to the ocean to lay eggs is called "downstream migration". Generally speaking, many fish have migrations. The reasons for migration include: 1. Finding a suitable water temperature; 2. Finding food; 3. Finding a place to lay eggs. Among them, eels belong to the third type of migration, which is to find a place to lay eggs.

Long-distance traveler: Eel is the most famous long-distance traveler among fish, because it swims back to the sea to lay eggs for more than 5,000 kilometers, the longest distance among fish.

The life of an eel:

When eel eggs hatch in the sea, they are called "narrow-headed fish". They are about 1-2 cm long and transparent all over, like a willow leaf. They are also called "willow leaf eels". They drift with the tide to absorb food.

When the eel transforms into a transparent and thin baby eel, it is called "eel thread". At this time, the eel thread has the shape of an eel, about four or five centimeters long, and is as thin as a thread, so it is called "eel thread". Because the eel at this stage is still transparent, it is also called "glass eel".

Baby eels drift with the seawater and take one to three years to swim to the river and grow up in freshwater. The body color of young eels is yellow-green at first, so they are called "yellow eels". When they enter the reproductive period, their body color will turn silver-gray, so they are also called "silver eels".

From October to January of each year, mature eels will swim down rivers to the deep sea to lay eggs, and then die of exhaustion.