Prevention and treatment methods for common fish diseases in spring such as bacterial gill rot and scale protrusion disease
Prevention and treatment methods for common fish diseases in spring such as gill rot and scale protrusion disease
I. Bacterial gill rot disease
Pathogen: Myxococcus piscicola. The bacterial cells are slender, basically uniform in thickness, with bluntly rounded ends, generally slightly curved.
Symptoms: The diseased fish has a darkened body color, stays apart from the school, and refuses to feed. There is abundant mucus on the gills, and the gill filaments are decayed and covered with mud. In severe cases, the cartilage at the tips of the gill filaments is exposed, the epidermis on the inner side of the operculum is congested, and the central epidermis is often eroded into a round, transparent small hole, commonly known as "open skylight." The gill tissue bleeds and rots. Because the gill tissue is destroyed, the fish has difficulty breathing, leading to death. After grass carp gill lamellae are infected with Myxococcus, the tissue lesions are not inflammation and congestion, but rather the cells and tissues in the affected area show varying degrees of decay, disintegration and invasive hemorrhage.
Susceptible species and epidemic conditions: This disease can occur in black carp, grass carp, bighead carp and other cultured fish, but mainly affects grass carp. It is generally rare at water temperatures below 15°C. It begins to spread at around 20°C.
Prevention and treatment methods:
1. Prevention: For each mu of water surface at 1 m depth, splash 50 ml of "Shajunhong" over the entire pond, once every 15 days. Add "Yukangle No. 2" at 0.5% to the feed, feeding once every 15 days. Before stocking fry and fingerlings, dilute "Miaozhong Paojiji" at a ratio of 1/5000 and bathe the fish for 3~5 minutes.
2. Treatment: For each mu of water surface at 1 m depth, evenly splash 100~125 ml of "Shajunhong" over the entire pond; using it together with "Yukangle No. 2" gives better results. If the condition is severe or an explosive outbreak occurs, use "Yukangle No. 1" at 1.5% added to the feed, with 3~5 days as one treatment course, and continue feeding until there is no further increase in dead fish.
II. Scale protrusion disease
Pathogen: Pseudomonas punctata
Symptoms: The body surface of the diseased fish is rough, and some scales (mostly on the tail) protrude outward like a pinecone. The scale bases are edematous, with translucent or blood-containing exudate accumulating inside, causing the scales to fall off. There are also symptoms such as fin rot, congestion at the base of the fin rays, and sometimes abdominal swelling and exophthalmos. The diseased fish swims slowly, has difficulty breathing, turns its body upside down with the belly upward, and dies after this state persists for 2~3 days.
Susceptible species and epidemic conditions: This disease mainly affects common carp, crucian carp, grass carp and silver carp. It spreads every spring.
Prevention and treatment methods:
Prevention: (1) In winter, after each netting and harvest, immediately splash "Shajunhong" over the entire pond at a rate of 50 ml per mu of water surface at 1 m depth. (2) After the thaw, splash 50 ml of "Shajunhong" per mu of water surface at 1 m depth over the entire pond.
Treatment: For each mu of water surface per meter of depth, evenly splash 100~125 ml of "Shajunhong" over the entire pond; in severe cases, use it 2~3 times consecutively. In areas where the fish have already started feeding, also add 1.5% "Yukangle No. 1" to the feed and feed continuously for three days.
III. Carp pox disease
Pathogen: Virus
Symptoms: In the early stage of the disease, many small white spots appear on the body surface of the diseased fish, covered with a layer of white blocky mucus. As the disease progresses, the number of white spots continuously increases, and at the same time the affected areas continuously expand, causing the epidermis at the lesion sites to gradually thicken and form paraffin-like growths shaped like pox, which is why it is called "carp pox disease." When the pox grows to a certain extent, it will naturally fall off, and then new pox will appear again at the original affected site, ultimately causing the fish to become emaciated and die.
Susceptible species and epidemic conditions: In pond aquaculture, it mainly affects 2-year-old common carp before and after overwintering, usually appearing from autumn to early winter and in spring, at water temperatures of 10~15°C. Because the incidence rate is low and other fish in the same pond are not infected, people have not paid much attention to this disease. In recent years, due to the vigorous development of high-density cage culture technology, this disease has become increasingly serious, and the incidence rate has gradually increased.
Prevention and treatment methods:
1. After the beginning of spring, for each mu of water surface per meter of depth, dilute 50 ml of "Shajunhong" or 200~400 ml (0.3~0.6 ppm) of "High-efficiency Sterilizing Iodine" and splash it over the entire pond, once a week, to control the amount of virus in the water.
2. After the fish begin to feed, add "Ultra-concentrated Photosynthetic Bacteria" at 2‰ of the feed amount and 0.3% highly stable easily reducible Vc to the feed to improve the immunity of the fish.
IV. Saprolegniasis
Pathogen: Saprolegnia
Symptoms: Saprolegniasis is commonly known as white hair disease or dermatomycosis. When Saprolegnia first becomes parasitic, generally no abnormality can be seen in the diseased fish; by the time symptoms are visible, the mycelium has already invaded the fish body through wounds and is growing outward. If the fish body is injured due to careless handling or transport, frostbite caused by low temperature, or primary lesions caused by parasite or bacterial infection, the zoospores of the fungus invade through the wounds on the fish body, absorb nutrients from the skin, rapidly multiply at the injured lesion site, spread and expand, and grow into cotton-wool-like hyphae. The hyphae entangle and adhere to the cells and tissues of the wound, causing skin ulceration and tissue necrosis. At the same time, as the lesion area expands, the burden on the fish body becomes too heavy, swimming becomes abnormal, appetite decreases, the fish becomes emaciated, and eventually dies from weakness.
Susceptible species and epidemic conditions: This disease occurs in low water temperature seasons below 20°C, and is most prevalent in early spring and late winter. It occurs throughout the country. Saprolegnia has no strict selectivity for parasites, and all cultured fish from eggs to adult fish can be infected. Fish in densely stocked overwintering ponds, in ponds with clear and lean water in spring, or in a state of starvation are all prone to saprolegniasis.
Prevention and treatment methods:
Prevention: During the process of transferring fish into ponds, operations should be as careful as possible to avoid injuring the fish body. Before entering the pond, dilute "Miaozhong Paojiji" at a ratio of 1/5000, bathe the fish for 3 minutes, and then put them into the pond. After entering the pond, splash "Shajunhong" over the entire pond at a rate of 50 ml per mu of water surface at 1 m depth. Avoid handling cultured fish at water temperatures below 15°C to prevent frostbite and abrasions on the fish body.
Treatment: For each mu of water surface at 1 m depth, splash 100~125 ml of "Shajunhong" over the entire pond.
V. Ichthyophthiriasis
Pathogen: Ichthyophthirius multifiliis.
Symptoms: When a large number of the parasites are present, white dot-like cysts can be seen with the naked eye covering the fish body surface, fin rays and gills, which is why it is also called "white spot disease." In severe infections, because the parasite invades the skin and gill epidermal tissue of the fish, it causes tissue proliferation at the lesion sites and secretes large amounts of mucus, forming a white film covering the surface of the lesions, while the fin ray lesion sites are destroyed and become rotten.
Susceptible species and epidemic conditions: This disease occurs in all aquaculture areas in the country. This parasite has no strict host selectivity, and is most harmful to fingerlings of the current year. It can infect fish in any type of rearing water body.
Prevention and treatment:
1. Before stocking, for each mu of water surface at 1 m depth, dissolve 50 g of "Yuchongmie 2B" in 2000 times water and splash it over the entire pond. Add "Yukangle No. 2" at 0.5% to the feed, feeding once every 15 days. Before stocking fry and fingerlings, dilute "Miaozhong Paojiji" at a ratio of 1/5000 and bathe for 3~5 minutes.
2. When the disease occurs, dissolve 50 g of Yuchongmie 2B in 2000 times water and evenly splash it over the entire pond at the rate for each mu of water surface at 1 m depth, then use it again after 2 days. Using it together with "Yukangle No. 2" gives better results. If the lesions are severely infected, use "Yukangle No. 1" at 1.5% added to the feed and feed continuously for 3~5 days.
Pathogen: Myxococcus piscicola. The bacterial cells are slender, basically uniform in thickness, with bluntly rounded ends, generally slightly curved.
Symptoms: The diseased fish has a darkened body color, stays apart from the school, and refuses to feed. There is abundant mucus on the gills, and the gill filaments are decayed and covered with mud. In severe cases, the cartilage at the tips of the gill filaments is exposed, the epidermis on the inner side of the operculum is congested, and the central epidermis is often eroded into a round, transparent small hole, commonly known as "open skylight." The gill tissue bleeds and rots. Because the gill tissue is destroyed, the fish has difficulty breathing, leading to death. After grass carp gill lamellae are infected with Myxococcus, the tissue lesions are not inflammation and congestion, but rather the cells and tissues in the affected area show varying degrees of decay, disintegration and invasive hemorrhage.
Susceptible species and epidemic conditions: This disease can occur in black carp, grass carp, bighead carp and other cultured fish, but mainly affects grass carp. It is generally rare at water temperatures below 15°C. It begins to spread at around 20°C.
Prevention and treatment methods:
1. Prevention: For each mu of water surface at 1 m depth, splash 50 ml of "Shajunhong" over the entire pond, once every 15 days. Add "Yukangle No. 2" at 0.5% to the feed, feeding once every 15 days. Before stocking fry and fingerlings, dilute "Miaozhong Paojiji" at a ratio of 1/5000 and bathe the fish for 3~5 minutes.
2. Treatment: For each mu of water surface at 1 m depth, evenly splash 100~125 ml of "Shajunhong" over the entire pond; using it together with "Yukangle No. 2" gives better results. If the condition is severe or an explosive outbreak occurs, use "Yukangle No. 1" at 1.5% added to the feed, with 3~5 days as one treatment course, and continue feeding until there is no further increase in dead fish.
II. Scale protrusion disease
Pathogen: Pseudomonas punctata
Symptoms: The body surface of the diseased fish is rough, and some scales (mostly on the tail) protrude outward like a pinecone. The scale bases are edematous, with translucent or blood-containing exudate accumulating inside, causing the scales to fall off. There are also symptoms such as fin rot, congestion at the base of the fin rays, and sometimes abdominal swelling and exophthalmos. The diseased fish swims slowly, has difficulty breathing, turns its body upside down with the belly upward, and dies after this state persists for 2~3 days.
Susceptible species and epidemic conditions: This disease mainly affects common carp, crucian carp, grass carp and silver carp. It spreads every spring.
Prevention and treatment methods:
Prevention: (1) In winter, after each netting and harvest, immediately splash "Shajunhong" over the entire pond at a rate of 50 ml per mu of water surface at 1 m depth. (2) After the thaw, splash 50 ml of "Shajunhong" per mu of water surface at 1 m depth over the entire pond.
Treatment: For each mu of water surface per meter of depth, evenly splash 100~125 ml of "Shajunhong" over the entire pond; in severe cases, use it 2~3 times consecutively. In areas where the fish have already started feeding, also add 1.5% "Yukangle No. 1" to the feed and feed continuously for three days.
III. Carp pox disease
Pathogen: Virus
Symptoms: In the early stage of the disease, many small white spots appear on the body surface of the diseased fish, covered with a layer of white blocky mucus. As the disease progresses, the number of white spots continuously increases, and at the same time the affected areas continuously expand, causing the epidermis at the lesion sites to gradually thicken and form paraffin-like growths shaped like pox, which is why it is called "carp pox disease." When the pox grows to a certain extent, it will naturally fall off, and then new pox will appear again at the original affected site, ultimately causing the fish to become emaciated and die.
Susceptible species and epidemic conditions: In pond aquaculture, it mainly affects 2-year-old common carp before and after overwintering, usually appearing from autumn to early winter and in spring, at water temperatures of 10~15°C. Because the incidence rate is low and other fish in the same pond are not infected, people have not paid much attention to this disease. In recent years, due to the vigorous development of high-density cage culture technology, this disease has become increasingly serious, and the incidence rate has gradually increased.
Prevention and treatment methods:
1. After the beginning of spring, for each mu of water surface per meter of depth, dilute 50 ml of "Shajunhong" or 200~400 ml (0.3~0.6 ppm) of "High-efficiency Sterilizing Iodine" and splash it over the entire pond, once a week, to control the amount of virus in the water.
2. After the fish begin to feed, add "Ultra-concentrated Photosynthetic Bacteria" at 2‰ of the feed amount and 0.3% highly stable easily reducible Vc to the feed to improve the immunity of the fish.
IV. Saprolegniasis
Pathogen: Saprolegnia
Symptoms: Saprolegniasis is commonly known as white hair disease or dermatomycosis. When Saprolegnia first becomes parasitic, generally no abnormality can be seen in the diseased fish; by the time symptoms are visible, the mycelium has already invaded the fish body through wounds and is growing outward. If the fish body is injured due to careless handling or transport, frostbite caused by low temperature, or primary lesions caused by parasite or bacterial infection, the zoospores of the fungus invade through the wounds on the fish body, absorb nutrients from the skin, rapidly multiply at the injured lesion site, spread and expand, and grow into cotton-wool-like hyphae. The hyphae entangle and adhere to the cells and tissues of the wound, causing skin ulceration and tissue necrosis. At the same time, as the lesion area expands, the burden on the fish body becomes too heavy, swimming becomes abnormal, appetite decreases, the fish becomes emaciated, and eventually dies from weakness.
Susceptible species and epidemic conditions: This disease occurs in low water temperature seasons below 20°C, and is most prevalent in early spring and late winter. It occurs throughout the country. Saprolegnia has no strict selectivity for parasites, and all cultured fish from eggs to adult fish can be infected. Fish in densely stocked overwintering ponds, in ponds with clear and lean water in spring, or in a state of starvation are all prone to saprolegniasis.
Prevention and treatment methods:
Prevention: During the process of transferring fish into ponds, operations should be as careful as possible to avoid injuring the fish body. Before entering the pond, dilute "Miaozhong Paojiji" at a ratio of 1/5000, bathe the fish for 3 minutes, and then put them into the pond. After entering the pond, splash "Shajunhong" over the entire pond at a rate of 50 ml per mu of water surface at 1 m depth. Avoid handling cultured fish at water temperatures below 15°C to prevent frostbite and abrasions on the fish body.
Treatment: For each mu of water surface at 1 m depth, splash 100~125 ml of "Shajunhong" over the entire pond.
V. Ichthyophthiriasis
Pathogen: Ichthyophthirius multifiliis.
Symptoms: When a large number of the parasites are present, white dot-like cysts can be seen with the naked eye covering the fish body surface, fin rays and gills, which is why it is also called "white spot disease." In severe infections, because the parasite invades the skin and gill epidermal tissue of the fish, it causes tissue proliferation at the lesion sites and secretes large amounts of mucus, forming a white film covering the surface of the lesions, while the fin ray lesion sites are destroyed and become rotten.
Susceptible species and epidemic conditions: This disease occurs in all aquaculture areas in the country. This parasite has no strict host selectivity, and is most harmful to fingerlings of the current year. It can infect fish in any type of rearing water body.
Prevention and treatment:
1. Before stocking, for each mu of water surface at 1 m depth, dissolve 50 g of "Yuchongmie 2B" in 2000 times water and splash it over the entire pond. Add "Yukangle No. 2" at 0.5% to the feed, feeding once every 15 days. Before stocking fry and fingerlings, dilute "Miaozhong Paojiji" at a ratio of 1/5000 and bathe for 3~5 minutes.
2. When the disease occurs, dissolve 50 g of Yuchongmie 2B in 2000 times water and evenly splash it over the entire pond at the rate for each mu of water surface at 1 m depth, then use it again after 2 days. Using it together with "Yukangle No. 2" gives better results. If the lesions are severely infected, use "Yukangle No. 1" at 1.5% added to the feed and feed continuously for 3~5 days.