In recent days, the air temperature and water temperature have risen rapidly. During a visit to the market, the author found that bubble disease has appeared in many farmers' fish ponds, which has had a certain impact on the aquaculture industry. This article discusses the causes, main symptoms, main hazards, and prevention and control measures of air bubble disease, aiming to provide some help to the majority of farmers.

Cause of disease: Oversaturation of a certain gas in the water can cause air bubble disease in aquatic animals. The younger the individual, the more sensitive it is. The bubbles in ponds with old water and thin water are mainly ammonia, nitrogen (alkaline water in saline-alkali land) or hydrogen sulfide, sulfur dioxide, carbon dioxide (acidic water) and other gases. The bubbles in fertilizer water with excessive phytoplankton are mainly oxygen.

? There are two main causes of air bubble disease in aquaculture. One is air bubble disease caused by the rapid increase in water temperature leading to oversaturation of air in the water body. It mainly occurs on sunny days after rainy days when the air temperature and water temperature rise rapidly. When the water temperature is high, the saturation of dissolved gases in the water is low, so when the water When the temperature rises, the dissolved gases in the water become supersaturated and cause bubble disease. The other is bubble disease caused by oxygen oversaturation, which mainly occurs in shallow ponds, ponds with heavy fertilization and ponds in the early stages of algae reproduction.

Main symptoms: Generally, in the early stage of the disease, a small number of pond fish can be seen turning over and staying in the water with their heads down and tails up, or even jumping. As the disease progresses, the fin rays turn white, and upon close inspection, bubbles of different sizes can be seen with the naked eye on the tail, dorsal, pectoral and pelvic fins of the fish. In severe cases, each fin ray of the fish turns red, and there are a large number of air bubbles in the fin ray tissue. Air bubbles of different sizes can be seen in the snout, orbit, gill cover and intestines. Some sick fish have vertical scales on both sides of the body behind the pelvic fin or all over the body. When the scales are peeled off, a large number of air bubbles can be seen under the epidermis.

Main harm: The main harm of air bubble disease is the acute death of affected fish, especially the harm to fry, which can cause a large number of death of fry; another hazard of air bubble disease is secondary infection Other diseases, such as saprolegnia, bacterial diseases, etc. Air bubble disease is very common in causing damage to fish fins. It is often observed that after grass carp develops air bubble disease, it is followed by tail rot. After the air embolism damages the gill filaments, the diseased fish develops secondary bacterial gill rot. After most of the air embolism in the gill filaments is absorbed by the fish body, a small amount of air embolism often remains at the end of the gill filaments, blocking the blood circulation and causing necrosis of the gill filaments at the end. It has been observed that the gill rot after air bubble disease is mainly ulcerated at the end of the gill filaments. In addition, fish tissue damage caused by air bubble disease can easily lead to secondary infection with saprolegnia in early spring.

Prevention and control measures:

1. For fertilized ponds with too many phytoplankton, Hailianke chlorine dioxide can be used;

2. Start adding water at noon Oxygen machine aeration;

3. If possible, add well water with lower dissolved oxygen and old water with more zooplankton;

4. Sprinkle surfactant to speed up the process. To escape saturated gas, you can use table salt (4-8ppm). Table salt can reduce the solubility of gas in water and adjust the osmotic pressure of water. It has certain bactericidal and anti-inflammatory effects at high concentrations;

5. After the onset of air bubble disease, the pond should be promptly splashed with less irritating disinfectants such as Hailianke povidone iodine (2-3 mu*m/bottle) or bacteriostatic traditional Chinese medicine preparations (Hailianke Benduling). Powder) to prevent secondary infections of bacterial diseases, saprolegnia, etc.