Damage and Prevention of Bubble Disease in Breeding Stage of Carassius auratus

With the continuous expansion of eel farming in Beijing, the demand for carp seedlings in the local area is also increasing. Farmers with good culture conditions will start carp seedlings cultivation from the larvae of carp. During the larval rearing stage, two sensitive periods of larval feeding and larval feeding were adopted. These two periods are the key to the successful cultivation of eel seedlings. Due to the special physiological structure and living habits of carp larvae, bubble disease often occurs due to various reasons, often resulting in different degrees of loss, and even causing large quantities of dead fish. The author now summarizes some experiences and experiences in the prevention and control of bubble disease in the eel fry cultivation stage as follows.
First, the symptoms of bubble disease
1 swimming larvae swimming, side after another intermittent rotation and then repeated swimming, after a period of time with the physical consumption of a large number of rotating swimming frequency decreased, gradually floating in the water, if the symptoms increase, there will be larva belly up , floating in the water phenomenon. At this stage, larvae often have difficulties in diving, and it is difficult to control their own swimming behavior, which directly leads to difficulties in feeding larvae.
2. Inflatable air inflation. The originally slightly thicker walls were filled with gas and were unusually transparent. Due to the abnormal inflation of the diaphragm, the internal organs are severely squeezed, causing the organs to deform and even shrink.
3. Gastrointestinal spasm severely squeezed gastrointestinal tract has different degrees of inflation, swelling. The gastrointestinal tract is inflated and inflated. In addition to squeezing other internal organs, gas gastrointestinal tract is caused by its own internal gas. Gastric bubbles are larger in volume and smaller in quantity; the volume of gas bubbles in the intestine is small and numerous.
4. Because the development of larval gizzards is not yet complete, it is not possible to cover the entire gills. This is accompanied by the occurrence of air bubble disease. In the early stages, the exposed ends of the gill filaments will expand and bend. With the prolongation of time and the degree of aggravation, the capillaries at the ends of the silk reel are circulated due to circulatory disturbances, and the symptoms such as deepening of the color of the silk, abnormal increase of mucus, adhesion of dirt and the like are exhibited, and even more serious ones may have some other symptoms of rotting.
5. The anal gastrointestinal and digestive glands are severely squeezed to form gastro-intestinal gas tamponade, which leads to erythema of the larvae, swelling and external protrusion.
6. Other symptoms such as prominent eyes, fin base congestion, abdominal muscle congestion and other symptoms.
Second, bubble damage
1. Opening larval opening larvae mainly use yolk sac as a nutrient source in the early stage, while the capillary network on the yolk sac performs respiratory function during which the larvae are in a vertical swimming stage. Bubble disease can cause damage to the delicate capillary network on the yolk sac, resulting in reduced respiratory efficiency, causing a heavy burden on the vertical movement of the larvae, and even making it difficult to submerge. Due to the influence of bubble disease, larvae postpone the opening time, and the lag in opening leads to long-term hunger starvation, which will have a serious impact on the survival rate and growth rate of later larvae.
2. The larvae of the larvae during the re-entry stage were completely transferred to the benthic life. The external feed was used as a nutrient source, the swimming speed was accelerated, the oxygen demand was increased, and the fleas were used as respiratory organs, but the pupa was not perfect. The direct effect of bubble disease on larvae is difficulty eating. The long-term effort to overcome the bubble resistance to ingest excessive energy consumption results in a direct loss of fish body weight, increased oxygen demand, and increased respiratory rate. In this sensitive period, if water quality deteriorates, sudden changes in water temperature, lack of oxygen, etc., it will often cause a large number of larvae to die at this stage.
3. Juvenile carp carp Juvenile carp juveniles from the body morphology, physiological structure and habits and open larvae, translucent larvae are relatively complete development in all aspects, but the ability to adapt to environmental changes, the disease resistance is still poor. Once a bubble disease occurs, it will not cause serious consequences in a short time, but it will adversely affect the growth rate and bait coefficient of the carp during the later period of aquaculture. When the situation is serious, various complications occur and even a dead fish phenomenon occurs.
Third, the cause of the disease
1 larvae transport larvae nylon bag oxygenation process, filling the oxygen pressure exceeds the larvae itself buffering capacity, resulting in fish body osmotic pressure imbalance, the gas from the yolk sac capillaries, cocoon capillary vessels penetrate into the fish body. With different amounts of oxygen and oxygen, the symptoms of the bubble and the severity of the disease are different.
2. After larvae are transported to larvae, the larvae are difficult to regulate and adapt in a short time due to the change of water temperature and the sudden drop of pressure during the process of stocking larvae to aquaculture.
3. Breeding of cultured water carp fry is mostly concentrated around the Spring Festival to summer. Before and after the Spring Festival, the eel fry breeding water is usually heated by boilers to increase the water temperature. At this time, due to some factors, the water temperature changes drastically and induces bubble disease; in the summer, the river water is usually used for seedling cultivation, due to the large number of aquatic plants in the river, photosynthesis. The role of strengthening, the river water gas sometimes in supersaturated or super-saturated, causing bubble disease.
4. Inflatable air stones Some farmers use artificially inflated methods to supplement oxygen in order to prevent the lack of oxygen in transit larvae. However, larvae can easily swallow bubbles and cause air bubbles.
Fourth, control methods
1. Salt bathing If bubbles occur, 0.5% to 1.0% salt water bath can be used to gradually relieve the disease and regulate the osmotic pressure so that bubbles in the body, gastrointestinal tract, tendons and fins of the fish gradually escape and finally eliminate the symptoms. However, if the salinity is too large, it will not only increase the severity of the disease, but also increase the number of bubbles in the body, gastrointestinal tract, gills, and fins of the fish. In severe cases, the fish will die.
2. Appropriate amount of air In the oxygenated transport process of the carp larvae nylon bag, the amount of oxygen to be filled is appropriate, which is less than that of other fish larvae. At the same time, according to the water temperature conditions, the length of the transport distance and flexible control, to fish without oxygen is appropriate.
3. Do not rush to open the nylon bag after the larvae have been transported to the farm. According to the actual situation, especially when the temperature difference between the transportation water temperature and the culture water temperature is large, it is necessary to carry out the same temperature and slow seedling; at the same time, slowly reduce the nylon bag gas pressure, try to make the osmotic pressure of the fish have a regulation process, and gradually adapt to avoid bubble disease happened.
4. Stable water temperature and juvenile fish breeding process to keep the water temperature as stable as possible, according to the actual breeding water temperature, water, water quality and other conditions to determine the scale of farming and culture.
5. Mesh isolation If artificial oxygen is used to replenish oxygen, a mesh cover should be placed on the gas stone to prevent the young and small fish from swallowing small bubbles.
V. Summary and Experience
1. In the course of using salt water to prevent air bubbles, the concentration is strictly controlled within the range of 0.5% to 1.0% and cannot be arbitrarily increased. At the same time, the process of salinity increase and decrease must be carried out slowly, without sudden rise or sudden drop. It is necessary to pay close attention to the fact that the temperature difference cannot change too much.
2. In the process of prevention and control of bubble disease, there are some cases of misdiagnosis and prevention. Sometimes it is easy to diagnose the abnormality of cocoon caused by air bubble disease, anal swelling and external protrusion symptoms as bacterial gill disease, enteritis disease, misuse of some disinfectants, antibacterial drugs cause the disease to deteriorate.
3. If bubbles occur in the juvenile fish culture process, it is difficult for the fish body to dive and cause difficulties in feeding. At this time, the water level can be reduced and the flow rate can be reduced without the need of oxygen deficiency to help the fish body overcome the difficulty of dive. Let it eat as much as possible to enhance the health of the body and restore health

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