What exactly is the “Arctic Catfish”?

The "Arctic Catfish" incident has come to an end.

In March this year, an internet user named "Arctic Catfish" showed off his family's wealth of nine figures, and even posted comments such as "So much money in my family was provided by leeks", "What should I do, I'm rich", and "(Grandpa) has four big words written on his face: I feel greedy". Netizens questioned him for his arrogant display of wealth and that his family was involved in corruption.

After several months of investigation, the results finally came out: the grandfather of netizen "Arctic Catfish", Zhong Gengci, did violate the law.

According to the official report of Shenzhen, Zhong Gengci was not loyal and honest to the party, and he colluded with others to resist the organization's review many times; he took the opportunity to make money and engaged in profit-making activities in violation of regulations; he took part-time jobs without approval and received remuneration in violation of regulations; he used the convenience of his position to seek benefits for others and illegally accepted money and property from others. Zhong Gengci seriously violated the party's political discipline and integrity discipline, and constituted a serious violation of duty, and should be severely dealt with. In accordance with the relevant provisions of the "Regulations on Disciplinary Actions of the Communist Party of China", "Supervision Law of the People's Republic of China", "Administrative Punishment Law of Public Officials of the People's Republic of China", etc., after deliberation by the Standing Committee of the Shenzhen Municipal Commission for Discipline Inspection, it was decided to expel Zhong Gengci from the party, determine his retirement benefits according to the second-level clerk, and confiscate his illegal gains.

Earlier, Zhong Gengci also said in an interview with the media that some of the online comments were rumors spread by netizens, and his granddaughter burst into tears because of his controversial comments. "I also wrote materials to the leaders, and they must investigate it thoroughly. I am afraid that it will affect the reputation of our unit and my granddaughter's studies."

Now, the true identity of the "big fish" behind the "Arctic catfish" has surfaced. Faced with the above-mentioned handling results, many netizens said that "it is really gratifying."

At the same time, some netizens really began to wonder, does the granddaughter's online name "Arctic Catfish" really exist? What kind of fish is this?

Do Arctic catfish exist?

According to the current species classification, there are about 2,400 species of catfish, divided into about 34 families, among which there is no branch of Arctic catfish. So, are there catfish living in the Arctic? Most catfish are tropical freshwater species, a small number of which are distributed in temperate regions (family, catfish family, catfish family and catfish family), and there are 2 families (eel catfish family and sea catfish family) that are marine species. Most importantly, catfish are warm-water fish, with a survival water temperature of 0 to 35°C, an optimal growth temperature of 23 to 28°C, and a pH value of 7.0 to 9.0.

Although the Arctic (the area north of the Arctic Circle) has been reported to be warming in recent years, even reaching temperatures of over 30 degrees Celsius, the Arctic is still very cold most of the time, with temperatures reaching minus 50 to 60 degrees Celsius. It is unlikely that catfish can survive naturally in such low temperatures unless they are artificially bred.

To put it into a idiom, catfish in the Arctic die quickly.

This is mainly because temperature really directly and significantly affects catfish feeding and growth and development.

The growth of fish depends on the amount of food they eat, the efficiency of digestion, absorption and conversion of feed into body tissues, and the ambient temperature has a direct impact on fish feeding. Studies have shown that as the ambient temperature rises, the amount of food catfish eat increases significantly and the feed conversion efficiency improves significantly. When the ambient temperature reaches 22.8℃, the amount of food catfish eats and the feed conversion efficiency are the highest; after exceeding 22.8℃, the amount of food catfish eats and the feed conversion efficiency will decrease.

In addition, regarding the effect of temperature on the growth and development of catfish, researchers such as Deng Enping conducted breeding experiments on 3-week-old southern catfish fry at 15℃, 18℃, 21℃, 24℃, 28℃, 32℃ and normal temperature (16.8℃~23.6℃). They found that under certain temperature conditions, as the temperature rises, the development speed of southern catfish fry accelerates. Not only does the time to complete development shorten with the increase in water temperature, but the time to complete each developmental stage is also shortened accordingly. However, above a certain temperature, the development speed slows down.

In the higher temperature groups (21℃, 24℃, 28℃, 32℃), the early larval stage of development was completed in the first week and entered the late larval stage. Under 24℃, 28℃, and 32℃ conditions, it entered the juvenile stage in the second week. Under low temperature (15℃) conditions, the early larval stage of development was completed in the third week and entered the late larval stage of odd fin differentiation.

The process of organ development is different at different temperatures. Under the optimum temperature, organ differentiation is completed earlier as the water temperature rises. Under the conditions of 28℃ and 32℃, it was found that the fish started to eat on the second day of the temperature control experiment, while the 15℃ group did not start eating until the fourth day. In addition, the time of opening the mouth to eat in the several temperature groups was earlier as the temperature rose.

Therefore, in order to ensure production, the temperature of most catfish farming ponds will be controlled at around 20℃~25℃.

Generally speaking, catfish prefer to live in darker waters, including deep pits near the banks of rivers, cracks in rocks, soil holes or stone caves at the bottom of tree roots, and waters with slower currents. If they are in still waters of reservoirs, ponds, and lakes, they often like to live in the dark bottom or under large areas of water hyacinths, water lilies, and water peanuts.

Catfish will only float to the surface on their own initiative when there is a problem with the water quality, there is a serious lack of oxygen in the water, or the water temperature is too high.

When a catfish surfaces on its own initiative, something is probably wrong.

Catfish has benefits

Many people have another impression about catfish: it is dirty.

There is some truth to that.

First of all, catfish are omnivorous animals, mainly eating aquatic insects, organic debris, etc., and will also eat some dead bodies of the same kind (when hungry) and living things such as rodents, small fish, and shrimps. Of course, it also eats animal feces.

In fact, in aquaculture, animal manure is a cheap, non-toxic natural fertilizer that provides a lot of nutrition for plankton in the water, so many farmers use chicken and pig manure as feed. Moreover, formal farms will ferment the manure before use to completely kill parasites and pathogens, and at the same time decompose the large molecular proteins in the manure into small molecular proteins and nutrients that are easily usable.

Secondly, because they are not picky about food, catfish can indeed live in relatively dirty water environments, but they also have a lower limit. If the water quality is particularly bad, it will affect the normal reproduction and healthy growth of catfish. Harmful substances in the water can also cause fish poisoning and death.

Catfish are named for their long whiskers, which are particularly prominent on the black bullhead catfish. Image source: Reference [1]

Although catfish may not look attractive, there are many benefits to eating it.

Apart from anything else, eating more catfish may make you smarter. Catfish has a high content of DHA, which can participate in the formation and development of brain cells, and plays an important role in the extension of nerve cell axons and the formation of new protrusions. It can maintain the normal physiological activities of nerve cells and participate in the brain's thinking and memory formation process. In addition, the human body cannot synthesize DHA on its own, so eating fish rich in DHA regularly is beneficial to the regeneration of brain cells, enhancing intelligence and memory, and can also prevent Alzheimer's disease.

In addition, some catfish have extremely high nutritional value.

Taking the wild catfish from Dongting Lake (commonly known as native catfish) as an example, the protein content in the muscle of wild catfish is 16.49g/100g fresh meat, which is much higher than eggs and 1.29 times that of eggs; the fat content is 8.19g/100g fresh meat, ranking first among 10 freshwater fish (as shown below), and also higher than lean pork and Vannamei shrimp, which are 1.32 times and 7.65 times that of lean pork and Vannamei shrimp respectively; the calories are 599kJ/100g fresh meat, ranking first among 10 freshwater fish, basically the same as lean pork, slightly lower than eggs, but much higher than Vannamei shrimp.

It is not difficult to see that wild catfish is actually a high-protein, high-fat, and high-calorie food.

Comparison of the content of common components in the muscles of 10 freshwater fish species and other foods (fresh weight) | Source: Reference [2]

At the same time, three inorganic salts, calcium, phosphorus and iron, were also detected in the muscles of wild catfish. Among them, the content of the major element phosphorus was as high as 282 mg/100 g fresh meat, ranking first among the 10 freshwater fish species, and also higher than Vannamei shrimp and lean pork, and much higher than eggs, which is 2.17 times that of eggs; the iron content was as high as 8.10 mg/100 g fresh meat, ranking first among the 10 freshwater fish species, and also much higher than lean pork, Vannamei shrimp and eggs, which are 2.70 times, 5.40 times and 4.05 times that of lean pork, Vannamei shrimp and eggs respectively.

Comparison of inorganic salt content in the muscles of 10 freshwater fish species and other foods | Source: Reference [2]

It can be said that wild catfish is one of the good foods for human body to supplement phosphorus and iron.

Overall, eating catfish in moderation is a good choice. Of course, we are talking about normal catfish here.

References:

[1] Li Xin: Panoramic Animal Encyclopedia

[2] Zhang Jiaguo, Meng Lin, and Zhang Ruichang (eds.): Eating Fish Makes You Smarter

[3] Sun Dewen, Zhan Yong, Xu Zirong. Research on the important role of environmental temperature in fish farming[J]. Aquaculture, 2003(02):36-39.

[4] Zhang Xianbing, Hu Yaping, Yang Wei, et al. Effects of water temperature on the life activities of warm-water freshwater fishes[J]. Journal of Hydroecology, 2021, 42(04): 117-122.

[5] Science Popularization in China: Raised in dirty water and fed with garbage? Are catfish really that dirty? The truth is…

Source: YiDu