Fish live in water. Regardless of fresh water or seawater, the aquatic environment affects the growth and reproduction of fish and affects the physiology and ecological balance of fish. There are various variable factors in the aquatic environment if these variables exceed the limits of the fish body. Tolerable limits can cause fish diseases or endanger their survival.
The physical and chemical factors of the ocean, such as temperature, salinity, pH, dissolved oxygen, water flow, and water pressure, etc. Understanding the changing patterns of these factors is a scientific basis for aquaculture production.
(a) Water temperature
Fish is a temperature-changing animal whose body temperature changes with changes in the surrounding water temperature. The body temperature of most fish differs by about 0.1 to 1°C from the surrounding water temperature. All kinds of fish have their heat-resistant upper and lower limits and the optimum temperature. Within the optimum temperature range, the fish eats, breathes, and digestive functions are vigorous, metabolism is enhanced, and growth is rapid. Exceeding the appropriate temperature range can cause metabolic disorders, growth inhibition, and even death.
According to the fish's adaptability to temperature, it can be divided into tropical fish, warm water fish and cold water fish. Tropical fish are suitable for higher water temperature (25~30°C), but they are not tolerant to low temperature, and it is difficult to survive below 15~30°C. Such as tilapia, milkfish, scorpionfish and some coral fish. Warm-water fish are suitable for temperate waters (15~25°C), such as squid, barracuda, and spotted fish sacrifices, while cold-water fishes are suitable for low-temperature growth, such as the suitable water temperature for squid fishes, 10 to 18°C. The water temperature during the feeding should not exceed 20°C.
Groupers inhabit many sea otters in tropical and temperate sediments. The optimum temperature is 24~30°C, but there are differences among groupers. For example, the upper limit of LD50 for grouper is 38.5 ~ 39.5 °C, the lower limit is 11.5 ~ 13.0 °C. The optimum temperature for red-spotted groupers is 22 to 28.5°C. If the water temperature exceeds 32°C, the balance will be lost. The red-spotted grouper will easily die at 32.2°C. 32 °C is the upper limit of these groupers, the lower limit is 15 °C, 15 °C when the fish out of balance, stop feeding, inactivity, the water temperature dropped to 14 °C, the weak and spots with stripe easy to die, especially Thailand and The spotted macules produced in the Philippines are not resistant to low temperatures.
Tilapia has an appropriate temperature of 25~30°C. It is easy to die at temperatures below 12°C and above 35°C. At 12°C, the fish body is in a state of depression, with its side lying on the water bottom. If the temperature drops further, it will cause death. Above 35°C, the fish's respiratory rate will accelerate and cause death.
The water temperature of large yellow croaker is lower than 12 °C without feeding, 5.8 ~ 6 °C death, high temperature can not exceed 33 °C.
The suitable water temperature of the fish is 18~29°C, and growth is stopped below 13°C. It is difficult to survive below 9°C and the temperature of wintering water cannot be lower than 10°C.
The suitable water temperature of true seabream is 20~28°C, and the food intake is strong. In summer, the water temperature can reach 30°C. The growth can be stagnant when the water temperature is 12°C. It stops feeding when the temperature is lower than 10°C, and it dies when it falls below 4°C.
Barramundi is a tropical fish that is not tolerant to low temperatures, stops feeding at temperatures below 17°C, is unresponsive at 15°C, loses its balance at 14°C and begins to experience a small number of deaths. The squid is resistant to low temperatures, and it can tolerate temperatures as low as 9 to 9.5°C and water temperatures as low as 13.5 to 14°C.
According to the above situation, local farmers need to understand the local temperature and water temperature changes in the local area, and stocking suitable breeds in order to avoid loss caused by production.
(b) Salinity
Dissolved salts in water vary from water to body and their classification criteria are also inconsistent. Generally, water with a salinity of 31 to 41 tons is called seawater or alkaline water, and water with 0.5 torr is fresh water.
Fishes have certain physiological mechanisms for regulating the salinity of different degrees of salamanders, but they are limited to a certain range. Exceeding this range can affect their survival. According to the fish's ability to adapt to changes in salinity, it can be divided into two categories: wide salinity and narrow salinity, and red-spotted rock-spot, black-spot, etc. belong to wide-salinity fish, and the tolerance to salinity changes greatly.
Groupers live in shallow harbour bays, and salinity can be adapted from 11 to 41 ft. Barramundi and yellowfin fishes can adapt to low salinity of less than 10 ,, they grow well and have no adverse reactions. However, true é²· and ç‹ fish are narrow-salt fishes, and require salinity above 16 æ°´ä¸ in water, and low salt. 8 degrees can lead to death. The salinity of these narrow-salt fishes is in the range of 25 to 32 ‰, and the larvae have the highest survival rate at 20 ‰.
The abrupt changes in salinity often cause fish to adapt and cause massive deaths, resulting in loss of production. Therefore, special care must be taken when setting up cages in shallow seas.
(III) Dissolved oxygen
The amount of dissolved in the environment directly affects the growth of farmed fish, food conversion, and the aquaculture capacity of the farm. Most fish do not directly absorb oxygen from the atmosphere, but are adapted to use helium to absorb dissolved oxygen in the water for gas exchange.
The amount of dissolved oxygen in seawater is related to water temperature and salinity. The rate of oxygen in the atmosphere is generally inversely proportional to water temperature and salinity and is proportional to atmospheric pressure. Seawater generally contains saturated dissolved oxygen, and fish do not suffer from oxygen deprivation. However, under certain local conditions, anoxic conditions may also occur in the water layer. For example, when fish floats are too dense, water flow is poor, or stagnation (flat tide) occurs, the weather Sweltering, cloudy clouds or thunderstorms before the cage hole was blocked by attachments, stocking density is high, it may cause a lack of oxygen in the culture area. The aging of the site and the deposition of organic substances on the bottom can also cause oxygen deficiency in the bottom layer, causing the death of benthic animals and bottom fish. In general, when the amount of dissolved oxygen was 3 mg/l, the food intake of fish decreased, and when 2 mg/l was stopped, feeding was stopped. Breathing difficulties, fish floating heads or vomiting were observed.
Table 1. Point of asphyxia for several types of marine fish
Fish temperature or fish body size asphyxiation point (mg/dm3) Assayer Barramundi 20°C 0.219~0.240 Li Jiaer 1991
Barracuda 37°C 0.7~0.93
25~28°C 0.52~0.42 Barracuda Group 1984
Yellowfin 0.927~0.97 Li Jiaer et al 1985
Herring 12~19°C 0.842mg/L (showing dyspnea) Itazawa 1959
Qing Shiban 08486mg/L Dai Qingnian et al 1994
(0.8468mg/L floating head)
Cocoon shaped grouper 32.40.9cm 0.18~0.23mg/L (semi-lethal dose) Chuact Teng 1980
8.70.5cm 0.38~0.39mg/L (Half-lethal dose)
True oyster 40~60mm whip fish 1.65~55mg/L Cai Xingbang and other juvenile fish and larvae stage 2.5mg/L Cai Dongcun et al 1992
Larvae pre-stage 3.04mg/L
* mg/dm3 (mm/dm), mg(mg/l)
Adequate oxygen levels are necessary for fish life. During the aquaculture production process, the amount of dissolved oxygen in the waters inside and outside the cages should always be taken into account. If the fish are in a state of low oxygen for a long time, there will be less food intake, lower metabolic rate, and life function. Reduced, dissolved oxygen should be maintained at 4 mg/l or more.
(d) Hydrogen ion concentration
The water's hydrogen ion concentration, the pH of the water, is expressed in terms of pH and is divided into 14 levels, [H+] concentration is 100 nanomoles/liter (nml/L) = pH7 is neutral, and [H*] concentration is greater than 100 nanomolar. The pH is less than 7 is acidic, and the [H+] concentration is less than 100 nanomoles/liter, ie, pH 7 is more than 7 is alkaline. The change of PH value is affected by the water quality factors such as carbon dioxide, dissolved oxygen, dissolved salts and salinity, mainly due to the ratio of free carbon dioxide, carbonate, and bicarbonate in the water. Generally, the more carbon dioxide, the higher the pH value. The lower, on the contrary, the lower the carbon dioxide, the higher the pH.
Hydrogen ion concentration has a very important impact on water quality, aquatic animals and plants. All kinds of fish have their optimum pH range, most fish adapt to a pH range of 7.0 to 8.5, favoring a weak alkaline environment, grouper The suitable range of pH value for fish is 6.8-8.0. A pH of less than 5 or greater than 9.5 causes the fish to die. Acidic water can make the pH value of fish's blood drop [H+] increase), which makes the combination of hemoglobin and oxygen obstructed, reduces the oxygen carrying capacity of blood cell, and causes the partial pressure of oxygen in the blood to become smaller, even if the content in the surrounding water is still high, As a result, fish also suffer from hypoxia, which reduces their metabolic function and inhibits their growth. Therefore, long-term in acidic water, the fish can be weakened, or easy to infect and cause detoxification.
Seawater is one of the best buffers for the variation of hydrogen concentration. The final polluted seawater has a pH of 7.85~8.35, which is suitable for fish growth and development.
(v) Water flow
In order to maintain good water quality, marine fish farms remove metabolic wastes such as ammonia-nitrogen (NH3-N) accumulated in cages and harmful gases such as hydrogen sulfide (H3S) accumulated at the bottom of the cage and decomposed baits, and decomposed. Should maintain ample flow or flow of water generated by the flow of water in and out of the cage, wash the fish row site to ensure that there is a high amount of dissolved oxygen in the cage, which is crucial for high-density intensive cage fish farming. important. If the tide or the coast is strong, it is not appropriate because the fish have to consume a lot of energy to maintain their stability and affect the growth rate of the fish. It is generally believed that the proper flow rate for the floating cage culture of the Gulf is: inside the cage. For 0.1 to 0.2 m/s, the flow rate outside the cage is 0.3 to 0.5 m/s. The amount of dissolved oxygen in cages with cage meshes between 7.5 and 50.5 mm is above 50% saturation. Sink-type cage culture requires a higher Zhu flow rate, preferably between 0.75 and 1.0 m/s, suitable for large-scale cage culture of fast-flowing marine fish.
Poor water exchange is not suitable for cage culture, because it does not meet the basic requirements of intensive culture, limiting the stocking density per unit of water surface and water self-purification. The total amount of biomass that can be borne by a specific area depends on the exchange of water flow. When the tide is small, the exchange of water flow is limited and it is difficult to conduct high density intensive culture.
In the case of increased number of attachments to the net and blocked meshes, the flow rate in the net decreases, and the amount of exchange decreases. In order to maintain a sufficient amount of dissolved oxygen in the tank, it is often necessary to periodically clean the cage.
(vi) Water pressure
Water pressure refers to the pressure (P) at one point in the ocean, that is, the static pressure at a certain depth, which can be expressed by the force of the water column acting on an area of ​​1 square centimeter. The weight of the water column per unit area is equal to the product of seawater depth (h), seawater density (p) and gravitational acceleration (g), ie P=pgh (units): dyne/cm2 or bar). 1 bar = 106 dynes/cm2, set at 1 bar per square centimeter when the pressure is 1 million dyne. Oceanography often uses the debit as a practical unit, that is, 1 bar = 1/10 = 105 dyne/cm2.
For each additional water depth of 1 meter, the pressure is usually increased by 1 bar. For every 10 meters of water depth, the pressure increases by one atmosphere. In 100 meters of deep water, the pressure in the urn is about 10 atmospheres. At 2,000 meters depth, fish were found to be gas-filled. There were 200 atmospheric pressures in the urn. When the fish enter the deeper layer from the shallow layer, gas traps need to add gas to maintain neutral buoyancy. The fish in the deep sea have long-term inhabitation under great pressure. The bones are thin and loose and flexible. The bones and bones are also loose and easy to separate. The muscles on both sides of the fish are underdeveloped, and the mouth is large and the stomach is stretched. Strong, many dissolved gases in the intestines and blood, so when caught in the water, the pressure plummeted and the gas swelled, often causing the muscle blood vessels to rupture. The viscera turned over and the eyeball protruded from the eyelids and died.
Marine organisms have adaptability to certain water pressures. Living in high water pressure fish does not easily survive at low water pressures. Similarly, living in low water pressure fish is not suitable for survival at high water pressures. When deep-water fish catches rises sharply, the water layer changes quickly, and fish do not have enough time to exhaust. When the fish reaches the surface, the gas pressure of the human body greatly exceeds the surface water pressure and the pressure in the air. The pressure suddenly decreases the swelling of the fish and can expand the body cavity. The stomach in the outside of the mouth, such as croaker caught in deep water, can happen. Groupers are caught in deep water (above 8 meters in depth). As the pressure drops sharply, insufflation of the inflated abdomen can also occur. Fishermen generally use bamboo needles or injection needles to deflate and raise them. This type of fish has trauma. It is not appropriate to do long-distance sales immediately.
The physical and chemical factors of the ocean, such as temperature, salinity, pH, dissolved oxygen, water flow, and water pressure, etc. Understanding the changing patterns of these factors is a scientific basis for aquaculture production.
(a) Water temperature
Fish is a temperature-changing animal whose body temperature changes with changes in the surrounding water temperature. The body temperature of most fish differs by about 0.1 to 1°C from the surrounding water temperature. All kinds of fish have their heat-resistant upper and lower limits and the optimum temperature. Within the optimum temperature range, the fish eats, breathes, and digestive functions are vigorous, metabolism is enhanced, and growth is rapid. Exceeding the appropriate temperature range can cause metabolic disorders, growth inhibition, and even death.
According to the fish's adaptability to temperature, it can be divided into tropical fish, warm water fish and cold water fish. Tropical fish are suitable for higher water temperature (25~30°C), but they are not tolerant to low temperature, and it is difficult to survive below 15~30°C. Such as tilapia, milkfish, scorpionfish and some coral fish. Warm-water fish are suitable for temperate waters (15~25°C), such as squid, barracuda, and spotted fish sacrifices, while cold-water fishes are suitable for low-temperature growth, such as the suitable water temperature for squid fishes, 10 to 18°C. The water temperature during the feeding should not exceed 20°C.
Groupers inhabit many sea otters in tropical and temperate sediments. The optimum temperature is 24~30°C, but there are differences among groupers. For example, the upper limit of LD50 for grouper is 38.5 ~ 39.5 °C, the lower limit is 11.5 ~ 13.0 °C. The optimum temperature for red-spotted groupers is 22 to 28.5°C. If the water temperature exceeds 32°C, the balance will be lost. The red-spotted grouper will easily die at 32.2°C. 32 °C is the upper limit of these groupers, the lower limit is 15 °C, 15 °C when the fish out of balance, stop feeding, inactivity, the water temperature dropped to 14 °C, the weak and spots with stripe easy to die, especially Thailand and The spotted macules produced in the Philippines are not resistant to low temperatures.
Tilapia has an appropriate temperature of 25~30°C. It is easy to die at temperatures below 12°C and above 35°C. At 12°C, the fish body is in a state of depression, with its side lying on the water bottom. If the temperature drops further, it will cause death. Above 35°C, the fish's respiratory rate will accelerate and cause death.
The water temperature of large yellow croaker is lower than 12 °C without feeding, 5.8 ~ 6 °C death, high temperature can not exceed 33 °C.
The suitable water temperature of the fish is 18~29°C, and growth is stopped below 13°C. It is difficult to survive below 9°C and the temperature of wintering water cannot be lower than 10°C.
The suitable water temperature of true seabream is 20~28°C, and the food intake is strong. In summer, the water temperature can reach 30°C. The growth can be stagnant when the water temperature is 12°C. It stops feeding when the temperature is lower than 10°C, and it dies when it falls below 4°C.
Barramundi is a tropical fish that is not tolerant to low temperatures, stops feeding at temperatures below 17°C, is unresponsive at 15°C, loses its balance at 14°C and begins to experience a small number of deaths. The squid is resistant to low temperatures, and it can tolerate temperatures as low as 9 to 9.5°C and water temperatures as low as 13.5 to 14°C.
According to the above situation, local farmers need to understand the local temperature and water temperature changes in the local area, and stocking suitable breeds in order to avoid loss caused by production.
(b) Salinity
Dissolved salts in water vary from water to body and their classification criteria are also inconsistent. Generally, water with a salinity of 31 to 41 tons is called seawater or alkaline water, and water with 0.5 torr is fresh water.
Fishes have certain physiological mechanisms for regulating the salinity of different degrees of salamanders, but they are limited to a certain range. Exceeding this range can affect their survival. According to the fish's ability to adapt to changes in salinity, it can be divided into two categories: wide salinity and narrow salinity, and red-spotted rock-spot, black-spot, etc. belong to wide-salinity fish, and the tolerance to salinity changes greatly.
Groupers live in shallow harbour bays, and salinity can be adapted from 11 to 41 ft. Barramundi and yellowfin fishes can adapt to low salinity of less than 10 ,, they grow well and have no adverse reactions. However, true é²· and ç‹ fish are narrow-salt fishes, and require salinity above 16 æ°´ä¸ in water, and low salt. 8 degrees can lead to death. The salinity of these narrow-salt fishes is in the range of 25 to 32 ‰, and the larvae have the highest survival rate at 20 ‰.
The abrupt changes in salinity often cause fish to adapt and cause massive deaths, resulting in loss of production. Therefore, special care must be taken when setting up cages in shallow seas.
(III) Dissolved oxygen
The amount of dissolved in the environment directly affects the growth of farmed fish, food conversion, and the aquaculture capacity of the farm. Most fish do not directly absorb oxygen from the atmosphere, but are adapted to use helium to absorb dissolved oxygen in the water for gas exchange.
The amount of dissolved oxygen in seawater is related to water temperature and salinity. The rate of oxygen in the atmosphere is generally inversely proportional to water temperature and salinity and is proportional to atmospheric pressure. Seawater generally contains saturated dissolved oxygen, and fish do not suffer from oxygen deprivation. However, under certain local conditions, anoxic conditions may also occur in the water layer. For example, when fish floats are too dense, water flow is poor, or stagnation (flat tide) occurs, the weather Sweltering, cloudy clouds or thunderstorms before the cage hole was blocked by attachments, stocking density is high, it may cause a lack of oxygen in the culture area. The aging of the site and the deposition of organic substances on the bottom can also cause oxygen deficiency in the bottom layer, causing the death of benthic animals and bottom fish. In general, when the amount of dissolved oxygen was 3 mg/l, the food intake of fish decreased, and when 2 mg/l was stopped, feeding was stopped. Breathing difficulties, fish floating heads or vomiting were observed.
Table 1. Point of asphyxia for several types of marine fish
Fish temperature or fish body size asphyxiation point (mg/dm3) Assayer Barramundi 20°C 0.219~0.240 Li Jiaer 1991
Barracuda 37°C 0.7~0.93
25~28°C 0.52~0.42 Barracuda Group 1984
Yellowfin 0.927~0.97 Li Jiaer et al 1985
Herring 12~19°C 0.842mg/L (showing dyspnea) Itazawa 1959
Qing Shiban 08486mg/L Dai Qingnian et al 1994
(0.8468mg/L floating head)
Cocoon shaped grouper 32.40.9cm 0.18~0.23mg/L (semi-lethal dose) Chuact Teng 1980
8.70.5cm 0.38~0.39mg/L (Half-lethal dose)
True oyster 40~60mm whip fish 1.65~55mg/L Cai Xingbang and other juvenile fish and larvae stage 2.5mg/L Cai Dongcun et al 1992
Larvae pre-stage 3.04mg/L
* mg/dm3 (mm/dm), mg(mg/l)
Adequate oxygen levels are necessary for fish life. During the aquaculture production process, the amount of dissolved oxygen in the waters inside and outside the cages should always be taken into account. If the fish are in a state of low oxygen for a long time, there will be less food intake, lower metabolic rate, and life function. Reduced, dissolved oxygen should be maintained at 4 mg/l or more.
(d) Hydrogen ion concentration
The water's hydrogen ion concentration, the pH of the water, is expressed in terms of pH and is divided into 14 levels, [H+] concentration is 100 nanomoles/liter (nml/L) = pH7 is neutral, and [H*] concentration is greater than 100 nanomolar. The pH is less than 7 is acidic, and the [H+] concentration is less than 100 nanomoles/liter, ie, pH 7 is more than 7 is alkaline. The change of PH value is affected by the water quality factors such as carbon dioxide, dissolved oxygen, dissolved salts and salinity, mainly due to the ratio of free carbon dioxide, carbonate, and bicarbonate in the water. Generally, the more carbon dioxide, the higher the pH value. The lower, on the contrary, the lower the carbon dioxide, the higher the pH.
Hydrogen ion concentration has a very important impact on water quality, aquatic animals and plants. All kinds of fish have their optimum pH range, most fish adapt to a pH range of 7.0 to 8.5, favoring a weak alkaline environment, grouper The suitable range of pH value for fish is 6.8-8.0. A pH of less than 5 or greater than 9.5 causes the fish to die. Acidic water can make the pH value of fish's blood drop [H+] increase), which makes the combination of hemoglobin and oxygen obstructed, reduces the oxygen carrying capacity of blood cell, and causes the partial pressure of oxygen in the blood to become smaller, even if the content in the surrounding water is still high, As a result, fish also suffer from hypoxia, which reduces their metabolic function and inhibits their growth. Therefore, long-term in acidic water, the fish can be weakened, or easy to infect and cause detoxification.
Seawater is one of the best buffers for the variation of hydrogen concentration. The final polluted seawater has a pH of 7.85~8.35, which is suitable for fish growth and development.
(v) Water flow
In order to maintain good water quality, marine fish farms remove metabolic wastes such as ammonia-nitrogen (NH3-N) accumulated in cages and harmful gases such as hydrogen sulfide (H3S) accumulated at the bottom of the cage and decomposed baits, and decomposed. Should maintain ample flow or flow of water generated by the flow of water in and out of the cage, wash the fish row site to ensure that there is a high amount of dissolved oxygen in the cage, which is crucial for high-density intensive cage fish farming. important. If the tide or the coast is strong, it is not appropriate because the fish have to consume a lot of energy to maintain their stability and affect the growth rate of the fish. It is generally believed that the proper flow rate for the floating cage culture of the Gulf is: inside the cage. For 0.1 to 0.2 m/s, the flow rate outside the cage is 0.3 to 0.5 m/s. The amount of dissolved oxygen in cages with cage meshes between 7.5 and 50.5 mm is above 50% saturation. Sink-type cage culture requires a higher Zhu flow rate, preferably between 0.75 and 1.0 m/s, suitable for large-scale cage culture of fast-flowing marine fish.
Poor water exchange is not suitable for cage culture, because it does not meet the basic requirements of intensive culture, limiting the stocking density per unit of water surface and water self-purification. The total amount of biomass that can be borne by a specific area depends on the exchange of water flow. When the tide is small, the exchange of water flow is limited and it is difficult to conduct high density intensive culture.
In the case of increased number of attachments to the net and blocked meshes, the flow rate in the net decreases, and the amount of exchange decreases. In order to maintain a sufficient amount of dissolved oxygen in the tank, it is often necessary to periodically clean the cage.
(vi) Water pressure
Water pressure refers to the pressure (P) at one point in the ocean, that is, the static pressure at a certain depth, which can be expressed by the force of the water column acting on an area of ​​1 square centimeter. The weight of the water column per unit area is equal to the product of seawater depth (h), seawater density (p) and gravitational acceleration (g), ie P=pgh (units): dyne/cm2 or bar). 1 bar = 106 dynes/cm2, set at 1 bar per square centimeter when the pressure is 1 million dyne. Oceanography often uses the debit as a practical unit, that is, 1 bar = 1/10 = 105 dyne/cm2.
For each additional water depth of 1 meter, the pressure is usually increased by 1 bar. For every 10 meters of water depth, the pressure increases by one atmosphere. In 100 meters of deep water, the pressure in the urn is about 10 atmospheres. At 2,000 meters depth, fish were found to be gas-filled. There were 200 atmospheric pressures in the urn. When the fish enter the deeper layer from the shallow layer, gas traps need to add gas to maintain neutral buoyancy. The fish in the deep sea have long-term inhabitation under great pressure. The bones are thin and loose and flexible. The bones and bones are also loose and easy to separate. The muscles on both sides of the fish are underdeveloped, and the mouth is large and the stomach is stretched. Strong, many dissolved gases in the intestines and blood, so when caught in the water, the pressure plummeted and the gas swelled, often causing the muscle blood vessels to rupture. The viscera turned over and the eyeball protruded from the eyelids and died.
Marine organisms have adaptability to certain water pressures. Living in high water pressure fish does not easily survive at low water pressures. Similarly, living in low water pressure fish is not suitable for survival at high water pressures. When deep-water fish catches rises sharply, the water layer changes quickly, and fish do not have enough time to exhaust. When the fish reaches the surface, the gas pressure of the human body greatly exceeds the surface water pressure and the pressure in the air. The pressure suddenly decreases the swelling of the fish and can expand the body cavity. The stomach in the outside of the mouth, such as croaker caught in deep water, can happen. Groupers are caught in deep water (above 8 meters in depth). As the pressure drops sharply, insufflation of the inflated abdomen can also occur. Fishermen generally use bamboo needles or injection needles to deflate and raise them. This type of fish has trauma. It is not appropriate to do long-distance sales immediately.
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