How to prevent and treat 7 common diseases in freshwater fish

1. Water mold disease

The disease occurs in most freshwater fish species such as carp, silver carp, grass carp, catfish, bighead carp, marbled goby... The disease develops favorably in ponds with stagnant water and high organic matter content...

Pathogen:Some mushroom genera such as: Leptolegnia, Aphanomices, Sarolegnia, Achlya.

Pathological signs:On the fish skin, at first there are grayish-white areas, which are small, soft fungal threads; then the fungus develops into white, cotton-like clumps. Sick fish swim abnormally, like to rub against objects in the water, causing their scales to peel off, creating conditions for bacteria to invade. In addition, parasites can cause fish eggs to rot.

Prevention and treatment:Perform pond cleaning techniques before each crop. Raise fish at appropriate density, avoid mechanical impact or parasites that can damage fish; maintain and stabilize pond temperature in many ways such as maintaining a pond water level of 1.5m, covering 2/3 of the pond surface with water hyacinth...

Use fungicide for fish. Some chemicals can be used to treat water borne fungus: Methylene 2 - 3g/m3, KMnO4 1 - 2g/m3, sprinkled into the pond and repeated twice a week. Or use 3% salt solution to bathe fish for 15 minutes.

2. Streptococcus

The disease occurs in some freshwater fish species such as tilapia, carp... and some marine fish species such as bass; the disease often breaks out when the weather is at 20 - 30 degrees Celsius.

Pathogen:caused by Streptococcus sp (streptococcus) bacteria in all stages of fish development.

Pathological signs:The fish's color gradually turns dark, they swim abnormally, their eyes are bulging and cloudy, and there are hemorrhages in the fins and gill covers. The hemorrhages spread into ulcers, but the ulcers are shallower than other types of leprosy. The sick fish swim in a twisted, disoriented manner. The acute form of the disease causes a high mortality rate.

Prevention and treatment:Maintain a minimum water level of 1.2 m in the pond; increase water changes and water fans at night and early morning to provide enough dissolved oxygen for the fish.

Periodically add multivitamins to food continuously for 7 days; kDisinfect water with Vicato effervescent tablets 20-30 times/day, dosage according to instructions.

Use the method of mixing antibiotics into food, such as Erythromycin, Ciprofloxacin, Enrofloxacin; dose 25-50mg/1kg fish/day, feed for 4-7 days.

Use TD3 herbs and multivitamins mixed into daily fish food to increase resistance and limit the spread and outbreak of bacteria in the pond.

3. Anchor worm disease

The disease is common in grass carp, bighead carp, silver carp, common carp... they parasitize on the skin, scales, gills, nasal cavity, eye socket, mouth... The disease develops strongly in late spring when the temperature is from 20 - 25 degrees Celsius.

Pathogen:Is an anchor worm of the genus Leronaea.

Pathological signs:Sick fish swim abnormally, are sluggish, eat poorly, and are deformed. There are small red spots on the fish's body. Some parasites in the fish's mouth cause the fish's mouth to swell and not close properly, making it impossible to eat.

Prevention and treatment:Apply comprehensive disease prevention measures. Before releasing fish, use neem leaves as base fertilizer in the pond at a rate of 0.2 - 0.3 kg/m3 of water to kill anchor worm larvae in the pond.

If possible, change all the water in the pond and disinfect the replacement water.

Using 0.4 - 0.5 kg/m3 of neem leaves to fertilize diseased fish ponds can kill Lernaea parasites. Because neem leaves decompose quickly, consuming a lot of oxygen and releasing toxic gases, especially in the summer when temperatures are high, it is necessary to monitor water supply promptly when necessary.

Bathe fish in potassium permanganate solution KMnO4 concentration 10 - 12g/m3 for 1 - 2 hours.

4. Ulcer syndrome

Many different fish species are affected by this disease, including some species that are highly susceptible to the disease such as snakehead fish, bighead carp, catfish, common carp... The disease spreads mainly through water currents and the movement of fish carrying the pathogen.

Pathogen:Due to the fungus Alphanomyces Invadan growing deep into the fish meat. In addition, there are other opportunistic pathogens such as viruses, bacteria, and parasites.

Pathological signs:Fish eat less, stop eating, and move slowly; on the body of the sick fish there are deep ulcers that cause the fish to die simultaneously. At the large ulcers, the center of the ulcer is gray where the fungus grows, the surrounding edges are black.

Prevention and treatment:For ulcer disease, the most effective measure to prevent the disease is to choose fish species with high disease resistance. In addition, there are measures to prevent fungus from entering the pond such as: Cleaning the pond before each crop.

During the farming process, every 2 weeks, dissolve lime (CaO) and sprinkle evenly over the pond surface at a dosage of 2 kg/100m3 of water.

Before releasing the fish, the fry need to be bathed in 2-3% NaCl for 5-15 minutes to disinfect external agents;Avoid mechanical impacts that damage the fish body.

5. Aeromonas bacteremia

Most freshwater fish species can be affected by this disease; outbreaks usually occur in late spring and early summer. Juvenile fish are more susceptible than adults, and mortality can be as high as 80%.

Pathogen:Caused by bacteria of the genus Aeromonas: A. hydrophila, A. caviae, A. sobria.

Pathological signs:Sick fish have dark areas on the belly, red patches appear on the body; tail and fin necrosis, wounds appear on the back, scales fall off easily; eyes are bulging and opaque.

Prevention and treatment:Avoid creating opportunistic agents such as parasitic infections; avoid scratching the fish, clean properly, do not stock too densely...

Use potassium permanganate (KmnO4) to bathe fish, dosage is 0.4g/100 liters of water, repeat treatment after 3 days; periodically bathe fish once a week, twice a week or once a month, depending on the health status of the fish.

Use drugs mixed into food such as Oxytetracycline: 55-77 mg/kg of fish weight, feed for 7-10 days (should limit use); Enrofloxacin: 20 mg/kg of fish weight, feed for 7-10 days; Streptomycin: 50-75 mg/kg of fish weight, feed for 5-7 days; Kanamycin: 50 mg/kg of fish weight, feed for 7 days...

6. Melon fruit rot (white spot disease)

The disease often occurs in carp, silver carp, grass carp, catfish, bighead carp... The disease develops favorably when the weather changes seasons - late spring to early summer.

Pathogen:caused by the melon fruit borer Ichthyophthirius multifiliis.

Pathological signs: kWhen sick, fish swim in schools on the water surface, thrashing around a lot due to itching; on the skin, gills, and fins of the fish, there are many parasites that stick together in very small, opaque white spots that can be seen with the naked eye. The skin and gills of sick fish are pale and pale in color. When too weak, the fish can only raise their heads to breathe, their tails are motionless and their heads are submerged in the water.

Prevention and treatment:Use formalin to spray into the pond twice a week at a concentration of 150 - 200 ml/m3, then change the water; or bathe the fish in formalin at a concentration of 200 - 250 ml/m3 for 30 - 60 minutes.

7. Bacterial red spot disease

Many different species are affected by this disease, including some species that are highly susceptible to the disease such as tilapia, bighead carp, common carp...

Pathological signs:Fish eat poorly or stop eating, red spots appear on the body, scales fall off, fish lose slime, dry, fins hemorrhage, gradually torn and truncated; small spots of hemorrhage on the skin, around the mouth and gill covers, on the belly.

Prevention and treatment:Use vaccines to prevent disease; reduce stocking density; provide good water source; bathe with KMnO4, dosage is 0.4g/100 liters of water, no time limit

Antibiotics can be used to treat infections such as septicemia caused by Aeromonas. Treatment: use 100g/50kg of fish continuously per day, supplement with Vitamin C.