What Kind of Fish Are Oilfish and Cod? An Introduction to Their Differences!

Oilfish and cod are not only both fish, but they also look very similar, yet cod is relatively more expensive than oilfish, which has led to fish being passed off as something they are not on the market. So, what are the differences between oilfish and cod?

1. What kind of fish is oilfish?

1. Oilfish is a fish of the order Cypriniformes, family Cyprinidae, genus Ptychidio, and is the collective name for the escolar (Lepidocybium flavobrunneum) and the oilfish (Ruvettus pretiosus). It is commonly found in tropical and temperate oceans around the world. In China it is distributed in the upper reaches of the Yangtze River and the Min River, Tuo River, Xi River and Qian River. It lives in mountain streams or rocky caves with flowing water and in places in rivers where springs emerge, feeding mainly on diatoms and the larvae of aquatic insects.

2. Oilfish is a deep-sea fish that inhabits the middle and lower layers of waters with relatively strong currents in the rivers of southern China; its body length is about 20 cm or more, and its body is slightly elongated like that of Ptychidio. The upper part of the body is black or bluish-black, the ventral surface is grayish-white, and each fin is slightly black. From behind the gill opening to in front of the pectoral fin, the black patches are relatively thick and merge into one large black blotch; most of the scales on the sides of the body have black edges, the scales are medium-sized, and the scales on the belly are smaller.

3. Oilfish contains more than 40% wax esters. Because the melting point of wax esters is as high as 1000 degrees C, the human body cannot break them down or absorb them, and eating them can cause diarrhea, gastrointestinal cramps and so on. Because its fat content is as high as more than 20% and it is used industrially to extract oil, it is called “oilfish”. Abroad it is mostly used for industrial purposes, and many countries do not recommend that their citizens eat it.

4. Oilfish is sweet in flavor and neutral in nature, and has the effects of benefiting the kidneys and strengthening the spleen and stopping bleeding. It is often used for chronic dysentery, vomiting blood and abnormal uterine bleeding.

2. What kind of fish is cod?

1. Cod is a fish of the order Gadiformes, family Gadidae, genus Gadus. There are three species of fish, namely Atlantic cod, Greenland cod and Pacific cod. It is distributed in the continental shelf waters on both sides of the North Pacific and North Atlantic. In China it is mainly distributed in the Bohai Sea, the Yellow Sea and the northern part of the East China Sea. In summer and autumn it inhabits the cold-water area of the Yellow Sea, and in winter it migrates to overwinter in the coastal muddy-bottom area at a water depth of 50-80 m, feeding on invertebrates and small fish.

2. Cod is a cold-water bottom-dwelling fish, generally living near the bottom (at a water depth of 0-2740 m); its body length is generally 25-40 cm, the body is elongated and slightly compressed; its body color varies, from light green or light gray to brown or light black, and can also be from dull red to bright red. The head, back and sides of the body are grayish-brown with irregular dark brown markings, and the ventral surface is grayish-white; the body is covered with small round scales.

3. Cod is a cold-water bottom-dwelling fish and one of the marine economic fish produced along the northern coast. Many countries around the world regard it as a main food fish. For example, Northern Europe calls it the “nutritionist on the dining table”. Besides being eaten fresh, it is also processed into various aquatic food products. In addition, cod has a large liver with a high oil content, rich in vitamins A and D, and is the raw material for extracting cod liver oil.

4. Cod is sweet in flavor and neutral in nature, and has the effects of invigorating the blood and relieving pain and promoting bowel movements. It is often used for fractures from falls, external bleeding and constipation.

3. An introduction to the differences between oilfish and cod!

Difference 1, different family and genus: oilfish is a fish of the order Cypriniformes, family Cyprinidae, genus Ptychidio, and is the collective name for the escolar and the oilfish; while cod is a fish of the order Gadiformes, family Gadidae, genus Gadus. There are three species in the genus Gadus, namely Atlantic cod, Greenland cod and Pacific cod.

Difference 2, different distribution: in China oilfish is distributed in the upper reaches of the Yangtze River and the Min River, Tuo River, Xi River and Qian River; while cod in China is mainly distributed in the Bohai Sea, the Yellow Sea and the northern part of the East China Sea.

Difference 3, different scales: cod's scales are relatively small, and its body has small silver round spots, and the scales are very sharp, feeling like needle pricks to the touch, while oilfish's scales do not have this feature.

Difference 4, different body color: oilfish's body color is black or bluish-black, the ventral surface is grayish-white, each fin is slightly black, and most of the scales on the sides of the body have black edges; cod's body color varies, from light green or light gray to brown or light black, and can also be from dull red to bright red. The head, back and sides of the body are grayish-brown with irregular dark brown markings, and the ventral surface is grayish-white.

Difference 5, different flesh color: cod's cross-section is large, the skin is white or grayish-white, the flesh is pure white with no obvious thick red lines, and the texture is fine; while oilfish's cross-section is small, the skin is grayish-black with a net-like pattern, the flesh is yellow with a pale yellow or pale red line, and the texture is relatively firm and coarse.

Difference 6, different feel: after cod is thawed, it feels very smooth to the touch, like a layer of mucus film giving a smooth feel; while oilfish feels relatively rough, lacking cod's smoothness and fineness.

Difference 7, different taste: oilfish tastes very greasy, and after cooking its flesh is very coarse and the taste is relatively poor; while cod's flesh is very fine and also has a unique light fragrance and umami, with a very good taste.

The above is an introduction to the differences between oilfish and cod, mainly distinguished by family and genus, distribution, scales, body color, flesh color, feel and taste. When buying on the market, everyone should choose carefully and not mistake oilfish for cod, so as not to waste money.