Control techniques for grouper diseases

China Aquatic Products Channel reported,

<b>1. Parasitic diseases</b>

1. Leukoplakiasis (also known as vallobitiasis)

Irregularly shaped white spots appear on the surface of the body, and in severe cases, the white spots are enlarged and contiguous, the mucus on the surface of the head, skin, fins and gills is significantly increased, swimming is slow, breathing is difficult, and the pectoral fin is stiff forward and backward after death, almost clinging to the gill cover. The causative agent is grouper valve worm, which parasitizes the gills, surface and fins of the red-spotted grouper. It was soaked with 2×10-6 concentrations of copper sulfate seawater solution for 2 hours, and repeated the next day, the effect was remarkable. Or bathe with fresh water for 4 minutes, you can also kill grouper valve worms, treatment of leukoplakia.

2. White spot disease (also known as small melon worm disease)

White spots with a diameter of 0.5 mm to 1 mm appear on the surface of the diseased fish, increased mucus, scales fall off, anorexia, and small melon worms parasitize in the gills to destroy the gills, causing the fish to have difficulty breathing until death. At water temperatures around 30°C, white spot disease spreads quickly, infecting groupers throughout the cage or pond within a few days. The causative agent is the irritant cryptonuclear worm.

Soak with fresh water for 5 minutes to 10 minutes, or use 100 × 10-6 concentration of formaldehyde seawater bath for 30 minutes to 1 hour, once every 3 days to 5 days.

<b>3. Cyclopathy (also known as myxosporidiosis</b>).

Sick fish swim abnormally on the surface of the sea and cannot descend into the deep water layer. The causative agent is myxoplasma cerebralum. The prevention method is to use a medicinal bath of potassium permanganate at a concentration of 0.34×10-6 concentrations for 10 minutes when stocking fish fingerlings to maintain fresh water quality.

<b>4. Ringworm disease</b>

The surface of the sick fish loses its luster, loss of appetite, and slow swimming. Some fins fester, increased mucus on the surface and gills, local scales shed, protruding eyeballs on one or both sides, inflammation, necrosis or detachment, swimming out of balance, spinning. Pathogens are cyclosomes. Soak with fresh water for 5 minutes to 10 minutes, once a day, for 2 to 3 days, the effect is good.

<b>5. Trematodiasis</b>

When a large number of trematodes are proliferated, it can cause the diseased fish to swim slowly, increase the mucus on the cheeks, congestion in some parts of the cheeks, and anemia in some parts of the liver, which is reddish, and in severe cases, it will cause death due to breathing difficulties. The causative bodies are grouper bisquacal chickworm, fractional bischin worm, grouper heterosexual double fluke and so on. Treatment can be referred to ringworm disease.

<b>6. Cryptofloasis</b>

The condition is similar to trematodiasis, the pathogen is cryptoflagellus, which can be killed by soaking in fresh water or 0.15× 10-6 concentration potassium permanganate solution for 5 minutes.

<b>7. Anchovy disease</b>

The mackerel parasitizes the surface and gills of the fish, sucking the nutrients of the fish body with suction cups, causing the integrity of the gill tissue to be destroyed, resulting in impaired respiratory function, and eventually causing the death of the diseased fish. The mackerel multiplies and infects quickly, especially during the season when sea temperatures are high. At present, there is no effective treatment method that does not pollute the environment, so attention should be paid to keeping the water quality clean in aquaculture production, which can effectively prevent the occurrence of the disease.

Parasites such as starch eggs plus algae, trypanosomiasis, coleospores, and wheelworms are also more harmful to groupers. In addition, nematode disease is the more common parasitic disease of groupers, with a high rate of infection. Especially under cage culture conditions, nematodes from forage fish are very seriously infected with grouper. Sometimes dozens of items appear in the body cavity, which are not taken seriously because the symptoms are not obvious.

<b>2. Bacterial diseases</b>

<b>1. Rotten tail disease</b>

The surface of the tail is hyperemic and inflamed, the skin ulcerates, and the scales fall off. The edges of the fish lesions are congested and red, the central edema and ulceration, and in severe cases, the muscles and bones are exposed, the fish loses its balance, and it dies for dozens of days. It mostly occurs from April to October, and the mortality rate is very high. Prevention can be prevented with a 0.34× 10-6 concentration of potassium permanganate for 10 minutes, and antibiotics can also be used to alleviate the disease.

<b>2. Ulcer disease</b>

The main symptoms of sick fish are slow movement, swimming out of the water, ulceration of each fin and base, and even scaly wounds all over the body. Ulcer surfaces vary in size and shape. The festering side will deepen and eventually die, with a high mortality rate. The pathogenic bacteria are Vibrio vulnificus. The onset season is from April to November. With furacillin dipping for 3 to 5 minutes and taking antibiotics internally, the disease can be controlled. Using formalin inactivated vaccines, heat inactivated vaccines and crude lipopolysaccharides extracted from Vibrio traumatic strain vegetation, blue grouper and salmon spotted grouper can be well protected by intramuscular injection.

<b>3. Bacterial leukoplakia</b>

Erythema of the fingersetle initially appears on both sides of the diseased fish, which, in rare cases, occurs on the head and tail, with a slight bulge at the lesion site. As the disease progresses, the lesion turns into a white spot, at which point the scales are slightly erect and easier to fall off. The white spots are clearer after the scales are removed. Diseased fish lose appetite, mortality rates of up to 90% or more, prevalent in winter. The precaution is to avoid damage to the fish body. The use of antibiotics and anti-inflammatory drugs may alleviate the condition, but the effect is not obvious.

<b>3. Other diseases</b>

<b>1. Nutritional disorder syndrome</b>

The diseased fish is inflated inside the maw, the abdomen is swollen, out of balance, and swirls on the surface of the water or at the bottom of the cage, so it is commonly known as "swelling disease" and "rotation disease". Tissue sections show liver steatosis, necrosis, vacuolarization, and nucleolysis. Diseased fish gills and internal organs develop local or systemic inflammation, and die after several days of floating on the surface of the water, with a higher mortality rate. From May to October in the epidemic season, the drug "Qing Zhangning" is used to prevent and control, and the effect is better.

<b>2. Hypertrophic kidney disease</b>

Sick fish have different degrees of bloating, floating or lying on their sides, fins and body surface ulceration, one or both sides of the eyeball protrusion, blindness or lameness, body surface black or white, that is, a serious prevalence of "bloating" in grouper farming. Blood leukocytes accounted for an average of 48.09%, and monocytes accounted for 2.82%, which was significantly higher than normal. The pathogen is a protozoan myxosome with a high incidence and is fed with the drug "Yu BaoShan" developed by the South China Sea Fisheries Research Institute of the Chinese Academy of Fishery Sciences, and the effect is remarkable.

<b>【Keywords】:Fishery </b><b>Grouper Pest Control</b> <b>Aquaculture Network</b>