Ophiocephalus argus [w ü l ǐ] (scientific name:Channa argus）, also known as black fish, wealth fish, mullet, snakehead fish, belonging to the snakehead family of Perciformes.[1-2]The adult snakehead is about 40~60cm long, and the maximum length can reach 1m;The general weight is about 0.5~1kg, and the maximum weight is 8~9kg.[4][19]The body of snakehead is fat and elongated, with cylindrical front and flat rear.The head is large and long, slightly flat in the front, slightly raised in the rear, and covered with irregular scales at the skull top.The snout is short and round, the mouth is large, the mouth fissure is slightly oblique, and the jaw is slightly protruding.There are many teeth in the mouth, fine tooth belts in the upper jaw, and sharp teeth on both sides of the lower jaw.[14]The body color is grayish black, the head back and body back are darker and darker, and the abdomen is pale. There are about 11 irregular large black spots on each side of the body, and one line of small black spots along the midline of the back.[21]
Ophiocephalus argus is a large benthic freshwater fish.It is a river basin originating from the East Asia Pacific water system. Its world distribution range can extend from the Korean Peninsula, the Heilongjiang River basin on the border between China and Russia, and the Wusuli River basin to the Xingkai Lake, and to the Yangtze River basin in the south.[4]In China, it is mainly distributed in Hunan, Hubei, Anhui, Henan, Shandong, Hebei, Liaoning and other provinces.[1]Later, it was widely introduced into Japan, Central Asian countries and eastern North America.Ophiocephalus argus is a fierce carnivorous fish that feeds on other fish, frogs, crustaceans and insects.[4]It has a special mouthpiece structure adapted to its predatory behavior, and mainly adopts ambush predatory mode.[8-9]The snakehead selects different foods at different growth stages.[6][10][14]
On December 12, 2007, Ophiocephalus argus was included in the List of Vivid Plant Resources of National Key Protected Economic Water in China (the first batch).[18]In 2020, snakehead was rated as a non endangered species by the IUCN Red List of Endangered Species.[11]
Chinese name
Ophiocephalus argus[2]
Latin name
Channa argus[3]
Alias
snakehead[2]、Mullet[2]、Snakehead[2]、Mermaid[2]
Foreign name
Snakehead、Northern Snakehead
International Endangered Level
No risk (LC)
circles
Animalia[3]
door
Chordata[3]
Outline
Actinopterygii[3]
order
Perciformes[3]
section
Channidae[3]
genus
Ophiocephalus（Channa）[3]
species
Ophiocephalus argus（Channa argus）[3]
Distribution area
The world: from the Korean Peninsula, the Heilongjiang Basin on the border between China and Russia, the Wusuli River Basin, to the Xingkai Lake, and to the Yangtze River Basin in the south[4]China: Hunan, Hubei, Anhui, Henan, Shandong, Hebei, Liaoning and other provinces[1]
Named by and date
Cantor，1842[3]
Protection level
The first batch of List of Vivid Plant Resources of National Key Protected Economic Water in China[18](2007)
Ophiocephalus argus has a large body. The adult Ophiocephalus argus has a body length of about 40~60cm, and the maximum length can reach 1m;The general weight is about 0.5~1kg, and the maximum weight is 8~9kg.[4][19]The overall shape is fat and elongated, the front is cylindrical, and the rear is laterally flat.[1]
head
The head of Ophiocephalus argus is characterized by large, sharp and long shape. The front half is slightly flat and the back half is slightly convex. The top of the head is covered with irregular scales, and has developed mucus pores.The snout is short and blunt, with a large mouth, slightly inclined mouth fissure, extending to the lower back edge of the eyes, and the jaw slightly protruding.[14]The mouth is full of teeth, the upper jaw has a fine tooth belt, while the teeth on both sides of the lower jaw are sharp, there is a row of fine teeth in front of the outer edge, and the tooth tip on the inner edge is strong, which is buried in the mucus membrane.The bones of the head, such as the vomer and palate, have hairy teeth and a row of large canine teeth.[20-21]
The eyes of Ophiocephalus argus are relatively small, located in the front and upper part of the head, very close to the snout end, and there is a wide eye gap between the two eyes.There are two nostrils on each side. The front nostril is tubular, slightly above the front edge of the snout, and the rear nostril is small, round, and located above the front of the eyes.The branchial fissure is large, and the left and right operculum are connected with each other, not with the cheek.The gill rakes are nodular and sparsely arranged.[20-21]
In addition, there is a large cavernous structure on the dorsal side of the branchial arch of the snakehead, which contains the epithelial tissue of the first branchial arch upper gill bone and tongue and jaw bone, forming the supragill organ.[20]The suprabranchial mucosa of this organ has developed capillaries, which can directly absorb oxygen in the air. It is an auxiliary respiratory organ when oxygen is lacking in water.[21]
body
The body of snakehead is covered with medium-sized round scales, especially on the head and trunk.Scales on the head are irregular bone flakes.The lateral line is located in the middle of the body side, bending downward above the starting point of the anal fin and extending to the base of the caudal fin.There are obvious holes or small pits in the head, forming the dorsal nape branch, the upper eye branch and the lower eye branch. At the same time, the anterior branchial bone branch extends below the mandible.[5]
The base of the dorsal fin is very long, starting from the front above the base of the ventral fin, and the rear fin exceeds the base of the caudal fin, with a total of 49~53 fins.The starting point of the anal fin is below the 16-17 dorsal fins, and the rear end of the anal fin base is roughly opposite to the end of the dorsal fin base, with a total of 31-35 fins.The pelvic fin is relatively small, starting from the bottom of the fourth to fifth dorsal fin, and the end does not extend to the anus, with a total of six fins.The pectoral fin is round, and the tip of the fin extends through the middle of the pelvic fin, with a total of 17 fins.The caudal fin is also round.[5]
Overall morphology of Ophiocephalus argus
Internal form
The peritoneum of Channa argus is white, the esophagus is relatively short, and there is no obvious boundary between it and the stomach.The shape of the stomach is cystic, including the cardia, stomach and pylorus, and the stomach wall is relatively thick.The pyloric sphincter is separated from the small intestine, and the intestine is relatively short, about 71% of the body length, in the shape of 2-3 bends.At the junction of stomach and intestine, there are two uniquely shaped pyloric caecum, which are finger shaped and longer than the stomach, which is a compensation mechanism for the shorter digestive tract of carnivorous fish.The swim bladder is a single chambered, long, thick tubular in the front, gradually expanded in the rear, and went deep into the caudal stalk, without swim bladder tube.The hepatopancreatic duct connects the stomach and small intestine.The liver is located at the lower part of the esophagus. It is yellowish brown and divided into left and right lobes.The gallbladder is located on the right lobe of the liver and is dark green.[5]
Abdomen color of snakehead
Body color
The body color of the snakehead is grayish black, the head and upper part of the body are dark, and the abdomen is light white.There are about 11 irregular large black spots on the side of the body, and a row of small black spots along the midline of the back.There are two black longitudinal stripes on the side of the head, while the lower part of the head and the chest and abdomen are dotted with brown dots.Fins are light yellow in color. There are black and white spots on odd dorsal fins, and irregular spots on even dorsal fins.[21]
Body color of snakehead
Habitat environment
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Ophiocephalus argus is a typical benthic freshwater fish, which can adapt to various types of freshwater habitats. It likes to inhabit in the still water with turbid water, lush water grass, silt as the bottom material, or the waters with slow flow, such as rivers, lakes, reservoirs, ditches, ponds and other water bodies, but rarely inhabits in the river sections with rapid flow.Ophiocephalus argus is the most cold resistant species in the family Ophiocephalidae. It also has a strong tolerance to high temperatures. It can survive in the water temperature range of 0~41 ℃. The suitable water temperature range is 16~30 ℃. It grows fastest at 20~25 ℃.[5]In addition, Ophiocephalus argus shows strong adaptability in adapting to water.It can survive in water bodies with pH values ranging from 3.1 to 9.6, whether in fresh or salt water environments.[6]The snakehead mainly lives in shallow water less than 2.5 meters deep, but it can also cross deep water areas to reach spawning sites.[4][7]
In addition, they can still live for a long time in wet areas with little or no water.In the environment of rainy summer, food shortage in habitat or other ecological conditions, snakehead can cross the pond base and move to nearby waters that are more suitable for them.[6]
Snakehead wandering in the water
Distribution range
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Ophiocephalus argus is native to the river basins of the East Asia Pacific water system. Its worldwide distribution range extends from the Korean Peninsula, the Heilongjiang River basin at the border between China and Russia, and the Wusuli River basin to the Xingkai Lake, and to the Yangtze River basin in the south.[4]In China, it is mainly distributed in Hunan, Hubei, Anhui, Henan, Shandong, Hebei, Liaoning and other provinces.[1]In addition, this species has been widely introduced into Japan, Kazakhstan, Uzbekistan, Turkmenistan in Central Asia, and eastern North America.[4]
Life habits
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Foraging behavior
Ophiocephalus argus is a fierce carnivorous fish, which mainly feeds on other fish, frogs, freshwater crustaceans and aquatic insects.[4]The structure of its predatory organs is adapted to its carnivorous nature.There is a specialized predator mouthpiece in the oral cavity. The oropharynx cavity is relatively wide, and the junction with the esophagus has radially arranged folds, which has greater flexibility and can swallow large whole tail bait fish.The basal hyoid bone supports a triangular and free tongue, with four pairs of whole gills. The number of gill rakes is small, and the gill rakes are specialized into spherical protuberances. The surface is covered with spiny spines, which is conducive to food control and also has a certain dismembering effect on food.The teeth in the mouth can tightly bite the prey and effectively prevent it from escaping.[8-9]
The prey of snakehead changes with its body length.At the larval stage with a body length of less than 3 cm, the fish mainly feed on copepods, cladocera and chironomid larvae;[6]When the body length reaches 3~8 cm, its feeding habits change to mainly feed on aquatic insect larvae, tadpoles, shrimp and small fish;[10]In the adult stage when the body length is more than 20 cm, various small miscellaneous fishes are the main prey, such as loach, white fish, red eye trout, striped fish and spiny loach.In addition, adults also catch frogs, shrimps and other prey.This gradual change in feeding habits enables the snakehead to make full use of the diversified food resources in the surrounding environment at different growth stages.[6][10][14]
Snakehead snakehead hunts by ambush.They usually hide near grass or other shelters. Once they find fish or shrimps close by, they will rush over and swallow their prey.Their food intake is quite large, and the maximum stomach capacity can even reach 60% of their body weight.[6]The snakehead has excellent swimming and jumping ability. Sometimes it can even jump out of the water to catch insects in the water. The height of the adult snakehead can reach more than 1m.[8-9]
Channa argus foraging
rhythm behavior
The snakehead usually shows the habit of living in the daytime and rising at night, preferring to be active at dusk and at night, especially in the aquatic vegetation near the shore.[4][8-9]They choose different active water layers in different seasons. They are active in the upper layer of the water body at the end of spring, and more active in the lower layer in summer.In late autumn, they often hide deep in the water. In the cold winter, the snakehead will hibernate under the water, sometimes even bury its body in the soil for winter.[6]Adult snakehead is more inclined to act alone and is a solitary predator, showing a strong sense of territory. However, under extreme conditions such as insufficient food sources, they will disperse to seek food.[4]
Communication and perception
The snakehead has the ability to make a little noise.Mature snakeheads are observed to purr when looking for food, and click when they come to the surface to breathe.They also have good eyesight, prefer hunting in low light conditions, and are even found attacking insects and other non aquatic animals outside the water (such as on branches).In addition, it has the ability of chemical perception.They can sense whether there are injured animals or food sources in the nearby waters by smelling the traces of blood chemicals in the water.[4]
Growth and reproduction
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growth characteristics
After spawning, the parent fish will hide under or near the nest and patrol to protect the eggs.This protection behavior will last until the fry hatch out and can swim freely and feed independently. It usually takes about 4 weeks. At this time, the fry will grow to 2cm, and the fry will have the ability to live independently.[4][6]
When the water temperature is 31 ℃, the eggs can hatch in 28 hours;Under the water temperature of 26 ℃, 20 ℃ and 18 ℃, the incubation time needs 36 hours, 2 days and 5 days respectively.[4][17]The newly hatched fish larvae are only 3.8~4.3 mm long, with large head and small tail, similar to tadpoles in shape.[17]Due to the existence of yolk sac, the swimming ability of newborn fry is weak, so they can only lie on their side and float under the water surface, and the yolk sac is the main nutrition, which lasts for about 12 days.Next, they gradually began to open their mouths to take food from outside until the yolk sac was completely consumed.[8-9]
Ophiocephalus argus has a rapid growth rate, but its growth status will be affected by the living environment and will be different.Generally speaking, the average body length of juvenile snakehead hatching in that year can reach 15 cm, and the weight is about 50 grams.According to the sample data collected in Taihu Lake in 1963, the body length and weight of snakehead in different age groups have changed. For example, the body length of 1 winter old juvenile fish is between 14.2 cm and 19.2 cm, and the body weight is between 115 g and 428 g;2 In winter, the body length is 24-28cm, and the weight is 350-760g;3 The body length of winter age fish is 32.9~38cm, and the weight is 600~1000g.Among the fish caught, about 500g is the most common weight, and the largest individual can even reach 5000g.[17]
Reproductive mode
The age of sexual maturity of snakehead is between 2 and 3 years old. Generally, when their body length reaches 20~30cm and their weight is about 500g, it means that they have entered the stage of sexual maturity.[17]
The spawning season of Ophiocephalus argus is slightly different in different regions.In South China, they mainly lay eggs from mid April to mid September, with May and June being the most productive months.In central China, the spawning period is mainly from May to July, especially June.[17]The snakehead selects lakes, ponds, ditches and other nearshore waters, especially the shallow water areas with lush aquatic plants and shelter from the wind as spawning grounds.The bottom of these places is usually silt.[6]The way of spawning is that after the female and male fish pair up, the female fish collects the aquatic plants around the spawning ground by mouth, and then pulls the aquatic plants into a circular nest floating on the water surface, with a diameter of about 1 meter.Egg laying usually occurs before sunrise in a quiet morning.The female fish first gets close to the water surface and lies on her back with her belly upward, slowly shaking her body to lay eggs, and then the male fish discharges sperm in the same position.[17]
The number of eggs carried by snakehead is about 20000.Their eggs are round, golden yellow, with oil balls. They are typical floating eggs, without viscosity, with a diameter of about 1.98 to 2.2 mm.[4][17]
In addition, there is a significant difference in the number of eggs laid between the place of origin and the place of introduction of snakehead.Take the Amur River as an example, the snakehead of the origin can spawn several times a year, up to 5 times.However, after being introduced to Potomac River, Kazakhstan and other places, the breeding frequency of Ophiocephalus argus is significantly reduced, and only spawns 1-3 times a year.In addition, the snakehead in the original place of origin reaches sexual maturity and begins to lay eggs at the age of 2-3, while in the introduction place, they may start to breed at less than the age of 2.[4]
Ophiocephalus argus and its seedlings
Artificial breeding
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Breeding conditions
First of all, male and female snakehead with strong body, no disease and injury, weight of more than 500 grams and sexual maturity should be selected as parent fish.These parent fish will be temporarily raised in the pond. The area of the parent fish breeding pool should be moderate, generally between 200~300 square meters, and the water depth is 65~100 cm.In order to provide a suitable habitat environment, aquatic plants can be planted in the pool.At this stage, the diet of parent fish mainly includes small fish, shrimp and other bait.If there is no special breeding pool, the parent fish of snakehead can also be mixed with other domestic fish (such as domestic fish and carp).[6][10][17]
The breeding pond for seedling cultivation should be kept within an area of 100 to 300 square meters, the depth of water storage should be 1.2 to 1.5 meters, and the thickness of sludge at the bottom of the pond should be 20 to 30 centimeters.A 60cm high polyethylene mesh fence shall be set around the pool to ensure good water source and quality.[10]
After the pond is disinfected, it can start to breed seedlings.In order to ensure good water quality, attention should be paid to the timely removal of residual bait and sediment, and the water should be renewed every 3 days.[6]The fry are most suitable for neutral to acidic water, and attention should be paid to the pH of the water.The stocking density should not be too high. Feed 4 to 5 times a day.[10]
Snakehead in the aquarium
Disease control
If the snakehead is poorly managed, it will cause various diseases, such as white skin disease, wheel worm disease, and red nematode disease, which are usually caused by excessive stocking density or poor cleaning of the pond at ordinary times. In order to prevent the occurrence of these diseases, attention should be paid to the hygiene of the pond at ordinary times. In the process of stocking, the stocking density should not be too high, if the disease has occurred,A series of drug treatments should be taken, such as the use of antibiotics to kill the pond.[10]
Protection status
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Protection level
On December 12, 2007, Ophiocephalus argus was included in the List of Vivid Plant Resources of National Key Protected Economic Water in China (the first batch).[18]
In 2020, snakehead was rated as a non endangered (LC) species by the IUCN Red List of Endangered Species.[11]
Species status
Ophiocephalus argus is widely distributed and widely introduced into other regions, so it is not seriously threatened on the whole, but its population is still affected by some factors and has declined.[11]
Major threats
The main threats faced by snakehead include overfishing and aquarium trade.In Kangka Lake and other areas, snakehead is the secondary target of fishery. The population is relatively small and may be threatened by overfishing.In addition, snakehead has also become the target of amateur and sports fishing, which has a certain impact on its number and distribution.[11]
Species hazards
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Species invasion
Due to accidental introduction, aquaculture or fishing activities, fishing, escape or intentional release in aquarium trade and live fish trade, the snakehead was introduced to many countries, including Japan, the former Soviet Union and the United States, and was rated as an invasive species in 2023.[15-16]
Ecological impact
The snakehead is a greedy top predator with few natural enemies. This species has great potential to seriously affect local fish, other crustaceans, insects and other biota.The snakehead can have a negative impact on the local population in all life stages, from feeding on fish eggs to eating adult fish.In addition, snakehead is also a vector of diseases and parasites, which may affect the health of human and local species;They will also affect the local aquatic ecosystem, and have a negative impact on commercial fisheries or other industries, resulting in economic losses or a decline in the quality of recreational use of water.[15]
Preventive measures
Ophiocephalus argus has been included in the list of harmful fish under federal control by the U.S. Fish and Wildlife Service, and its import and interstate transportation in the United States have been prohibited since October 2002.In the United States, fishermen and commercial fishermen are required to kill and freeze all snakeheads before release, and report to the local fishing and hunting department immediately.In addition, they will also use some chemical agents for chemical removal, such as rotenone, electric fishing and net fishing can also provide a certain degree of eradication effect.[15]
Interspecific relationship
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natural enemy
The snakehead has few natural enemies, but it is still preyed by some large fish eaters, such as large fish, birds, crocodiles, turtles and otters.In addition, the study found that Gambusia holbrooki would enter the nest of snakehead and prey on their eggs.[4]
parasitic
Like most fish, snakehead is also affected by a variety of parasites, including Myxozoans, CysticercusGryporhynchus cheilancristrotus, trematode（Posthodiplostomum）And other parasites.[4]
Key values
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economic value
Ophiocephalus argus is an important target fish of Qinkang Lake fishery and one of the main cultured fish species in China.[11]In addition, the frozen snakehead fillet is one of the main aquatic products exported by China.[12]Ophiocephalus argus grows fast and has a high yield, and mainly feeds on wild miscellaneous fish and shrimp.In some lakes in Inner Mongolia, China, overfishing has led to eutrophication of lakes and small fish sizes, which provides a natural bait advantage for the cultivation of snakehead.The success of snakehead farming has brought considerable economic benefits to the region and increased the income of local farmers.[13]
Edible value
Ophiocephalus argus is not only a delicious food fish, but also has multiple advantages.Its meat is fresh, tender, delicious and rich in nutrients.For every 100 grams of snakehead meat, the protein is up to 19.8 grams, the fat is only 1.4 grams, and the carbohydrate is 1.2 grams.[8-9][14]In addition, snakehead meat is rich in calcium, phosphorus, iron, zinc and other nutrients needed by the human body, making it a nutrient rich food.[8-9]The fish oil has a rich variety of fatty acids, especially some unsaturated fatty acids such as oleic acid, linoleic acid, and eicoseic acid, which are high, and are made into edible fish oil by people.[12]
Related culture
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Film and television culture
Ophiocephalus argus has become an attractive species due to its invasion in some areas.This phenomenon has not only attracted the attention of the scientific community, but also triggered some creative inspiration in the entertainment industry.Some directors created several horror films based on the invasion of snakehead, including Frankenfish and Snakehead Terror.These movies are probably based on the true story of the snakehead invasion, depicting it as a frightening monster, integrating elements of terror and horror.[22]
world record
According to the report of the International Fishing Association, on June 1, 2013, Caleb Newton, a resident of Spotsylvania County, Commonwealth of Virginia, successfully caught a huge snakehead at the intersection of Aquia Creek and Potomac River.This snakehead weighed an astonishing 17 pounds and 6 ounces, equivalent to about 7.9 kilograms, setting a world record.This achievement surpassed the previous 17 lb 4 oz (about 7.8 kg) snakehead captured in Sanmu City, Xiangchuan County, Japan, in 2004, and became the new record holder.[23]
