CATDOLL : CATDOLL: What medicine should be used if grouper has virus?

What medicine should be used if grouper has virus

What are the common diseases and treatments for grouper?

1. Vibrio disease

This disease is very harmful to marine fish such as grouper. It mostly occurs from April to November, with the most severe symptoms in April and May, and the mortality rate can reach about 90%.

1. Pathogen: The pathogen of grouper Vibrio disease is Vibrio anguillarum.

2. Symptoms: The body color of the diseased fish fades, the base of the fins is congested and ulcerated, the body surface is partially red, swollen and ulcerated, some eyeballs are cloudy and protruding, the liver, kidney and other internal organs are bleeding or congested, partially necrotized, and the abdominal cavity is filled with yellow ascites. The diseased fish swims on the surface of the water, moves slowly, and stops eating.

3. Diagnosis: A preliminary diagnosis can be made based on symptoms, and definitive diagnosis requires isolation and identification using Vibrio selective culture medium (TCBS) by sampling the liver, kidney or blood.

4. Prevention and control methods

(1) Be careful when operating to avoid injuring the fish. Do not feed stale or spoiled small fish, especially in spring and summer.

(2) Take oxytetracycline or tetracycline (pure powder) orally, 50-70 mg per kilogram of fish, mix with bait and take orally for 5-7 days as a course of treatment. Use antibacterial drugs such as furacilin externally to soak for 3-5 minutes.

(3) Use pure powder of sulfonamide drugs such as sulfamethoxazole, 200 mg per kilogram of fish, mixed with bait and taken orally for 3-7 days.

2. Leukoplakia

White spot disease is one of the serious diseases of grouper, especially in high-density temporary holding ponds and cages. The disease spreads quickly, and in severe cases, all the fish in the pond can die in 3-4 days. In the cages, it forms complications with monogenean trematodes, with an infection rate of 90% and a mortality rate of more than 50%. The disease is prevalent in Fujian, Guangdong, Zhejiang and other places, and often occurs in summer.

1. Pathogen: The pathogen is the ciliate Echinopoda. The worm is tiny and slightly transparent, similar to the freshwater carp worm, oval or ovate, 45-80×29-53 microns in size. There are 32-36 ciliary lines on the ventral surface of the worm, and the rest are exposed. There is a round cell mouth in the middle of the front part, an oval large nucleus in the middle of the worm, and a flower-shaped petal behind the large nucleus.

2. Symptoms: The parasites live on the body, gills and fins of grouper. Irregular white spots appear on the body of the diseased fish. In severe cases, the white spots are connected into one piece. The fins of the dead fish extend forward and cling to the gill cover. The mucus on the body and gills of the fish increases and flows slowly. The fish has difficulty breathing and often floats on the water surface.

3. Diagnosis: Initial diagnosis can be made based on the symptoms on the body surface. Confirmation requires the scraping of mucus from the body surface and gills for microscopic examination, where a large number of worms can be found.

4. Prevention and treatment methods: Soak the diseased fish in fresh water for 2-4 minutes to kill the pathogen. Red-spotted grouper is safe in still fresh water for 30 minutes and in flowing fresh water for 60 minutes. Even if the fish flips over, it can still return to normal when put back into sea water.

What is the solution for grouper with rotten belly?

In daily management, we must pay great attention to balanced nutrition, fresh water quality, and disinfection; once a disease is found, we must actively treat it, isolate it, and prevent the spread of pathogens.

1. Parasitic diseases

①. White spot disease (also called valvulariasis) Irregular white spots appear on the body surface. In severe cases, the white spots expand and become continuous. The mucus on the head, skin, fins and gills increases significantly. The fish swims slowly and has difficulty breathing. After death, the pectoral fins become stiff and almost close to the gill cover. The pathogen is grouper valvularia, which parasitizes on the gills, body surface and fins of red-spotted grouper. Soaking in a 2×10-6 concentration of copper sulfate seawater for 2 hours and repeating it the next day has a significant effect. Bathing in fresh water for 4 minutes can also kill grouper valvularia and treat white spot disease.

②. White spot disease (also called Ichthyophthirius punctatus) White spots with a diameter of 0.5 mm to 1 mm appear on the body surface of the diseased fish, mucus increases, scales fall off, and the fish loses its appetite. Ichthyophthirius punctatus parasitizes the gills and destroys the gills, causing breathing difficulties and even death. When the water temperature is around 30℃, white spot disease spreads quickly. Within a few days, the entire grouper in the net cage or fish pond will be infected. The pathogen is Cryptocaryon irritans. Soak in fresh water for 5 to 10 minutes, or use 100× 10-6 formaldehyde seawater for 30 minutes to 1 hour, once every 3 to 5 days.

③. Whirling disease (also called myxosporean disease) The diseased fish swim abnormally on the sea surface and cannot go down to the deep water layer. The pathogen is myxosporean cerebral worm. The prevention method is to bathe the fish with 0.34×10-6 potassium permanganate for 10 minutes when stocking the fish to keep the water fresh.

④. Fish with ringworm disease lose their luster, have poor appetite, and swim slowly. Some fish have ulcerated fins, increased mucus on the body and gills, local scales fall off, one or both eyeballs protrude, become inflamed, necrotic or fall off, lose balance when swimming, and spin around. The pathogen is ringworm. Soak in fresh water for 5 to 10 minutes, once a day, for 2 to 3 consecutive days, and the effect is good.

⑤. Trematode disease When the trematodes proliferate in large numbers, the fish may swim slowly, have more mucus on the gills, have congestion in some parts of the gills, and be anemic and light red in others. In severe cases, the fish may die from breathing difficulties. The pathogens are grouper diploid flukes, sex-dividing diploid flukes, grouper heterodividing diploid flukes, etc. The treatment methods can refer to dactylosis.

⑥. The symptoms of Cryptowhippiasis are similar to those of trematodiasis. The pathogen is Cryptowhippia, which can be killed by soaking in fresh water or 0.15×10-6 potassium permanganate solution for 5 minutes.

⑦. Gnat disease Gnat parasitizes on the surface and gills of fish, and absorbs nutrients from the fish with a sucker, causing damage to the integrity of the gill tissue, resulting in impaired respiratory function and eventually death of the diseased fish. Gnat reproduces and spreads quickly, especially in seasons with high seawater temperatures. There is currently no effective treatment method that does not pollute the environment, so attention should be paid to keeping the water clean during aquaculture production to effectively prevent the occurrence of this disease.

Parasites such as starch egg plus algae, trypanosomes, horn spores, and wheelworms are also harmful to grouper. In addition, nematode disease is a common parasitic disease of grouper, and the infection rate is very high. Especially under cage farming conditions, the infection of nematodes in feed fish to grouper is very serious. Sometimes dozens of nematodes appear in the body cavity, but because the symptoms are not obvious, they are not taken seriously.

2. Bacterial diseases

①. Tail rot disease: The tail surface is congested and inflamed, the skin is ulcerated, and the scales fall off. The edge of the fish lesion is congested and red, the center is swollen and ulcerated, and in severe cases, the muscles and bones are exposed, the fish loses balance, and dies in dozens of days. It often occurs from April to October, and the mortality rate is very high. For prevention, you can use a potassium permanganate bath with a concentration of 0.34×10-6 for 10 minutes, and antibiotics can also be used to relieve the condition.

②. The main symptoms of fish with ulcer disease are sluggish movement, swimming out of the water, ulcers on the fins and base, and even bruises all over the body. The ulcers vary in size and shape. The ulcers will deepen and eventually lead to death, with a high mortality rate. The pathogen is Vibrio vulnificus. The disease season is from April to November. Soaking in furazolidone for 3 to 5 minutes and taking antibiotics orally can control the disease. Formalin-inactivated vaccines from the vegetation of virulent strains of Vibrio vulnificus, heat-inactivated vaccines, and crude lipopolysaccharides extracted from Vibrio vulnificus can provide good immune protection for blue grouper and salmon grouper by intramuscular injection.

③. Bacterial white spot disease: Fingerprint-like red spots first appear on both sides of the fish body. In rare cases, they may occur on the head and tail, and the lesion site is slightly raised. As the disease progresses, the lesion turns into white spots, and the scales are slightly erected and easier to fall off. The white spots are clearer after the scales fall off. The fish lose their appetite, and the mortality rate is as high as 90%. It is prevalent in winter. The preventive measure is to avoid damage to the fish body. Antibiotics and anti-inflammatory drugs can alleviate the disease, but the effect is not obvious.

3. Other diseases

①. Nutritional disorder syndrome. The fish's swim bladder is inflated, the abdomen is swollen, and the fish loses balance, spinning on the water surface or the bottom of the cage, so it is commonly known as bloating disease and spinning disease. Tissue sections show fatty degeneration, necrosis, vacuolation, and nuclear dissolution of the liver. The fish's gills and internal organs show local or systemic inflammation, and the fish dies after floating on the water surface for several days, with a high mortality rate. The epidemic season is from May to October, and the drug Qingzhangning is used for prevention and treatment, with good results.

②. Fish with hyperplastic kidney disease have varying degrees of abdominal distension, floating upside down or lying on their side, ulceration of fins and body surface, protruding eyeballs on one or both sides, blindness or lameness, and black or white body surface, which is a serious and prevalent bloating disease in grouper farming. The average white blood cell count is 48.09%, and the monocyte count is 2.82%, which is significantly higher than the normal value. The pathogen is a protozoan myxozoan with a high incidence rate. Feeding with the drug Yubaosan developed by the South China Sea Fisheries Research Institute of the Chinese Academy of Fishery Sciences has a significant effect.