Koi fish are known as the national treasure – a famous ornamental fish species in the land of rising sun. However, when Koi fish are raised in water environments that are not hygienic and clean, they are very prone to disease. Below, BGD Landscape will compile a summary of common diseases in Koi and guide you on quick disease treatment, helping fish recover quickly and swim happily.
1. Gill Lice:
1.1. Causes:
Anchor worm is one of the most common diseases in koi fish. The disease is caused by a type of crustacean parasite called Lernaea – Anchor Worm. This parasitic organism attaches tightly to the body and tail of koi, and is easily visible to the naked eye. When young, anchor worms live in the gills of koi fish. During the adult stage, male and female anchor worms mate, and then the male leaves the koi gills to live in the water for several days before dying. Female anchor worms are fertilized and remain on the body of koi fish, absorbing nutrients. blood in the body of the fish, causing bleeding wounds.
1.2. Symptoms:
When suffering from this illness, Koi often become lethargic, itchy, uncomfortable, thin, and swim slowly. Wounds caused by Ichthyophthirius multifiliis create conditions for fungi and bacteria to attack, causing the condition to worsen.
1.3. Treatment methods:
Dimilin is a medication for treating parasites such as anchor worm and lice in Koi fish. Since it contains a pesticide, you need to consider and exercise caution when using it.
Dosage: 1g/m³
Application method:
– Day 1: Administer 1 dose; medication dosage depends on the volume of the diseased Koi pond/tank.
– Day 2: No medication.
– Day 3: Administer second dose as Day 1, while replacing 20% of the water.
– Days 4, 5, 6: No medication.
– Day 7: Administer third dose, replacing 20% of the water.
– Day 8: No medication.
– Day 9: Administer fourth dose, replacing 20% of the water.
– Days 10, 11: No medication.
– Days 12, 13, 14: Change 20% of the water daily.
Anchor worms laying eggs in water and hatching cause disease in fish, so 4 doses of medication should be administered over 14 days to eliminate both the anchor worms and eggs completely.
2. White Spot Disease in Koi
2.1 Causes:
White spot disease is one of the most common and frequent diseases in Koi fish. The main cause is usually unclean, unsanitary water. White mold adheres tightly to the skin of Koi fish, causing them to become weak…
2.2 Symptoms:
White spots appear on the fish's body, resembling salt crystals, and spread quickly to other parts. Since they live in schools, when one fish is affected, the disease can spread to others. The best approach when detected is for the owner to isolate the sick Koi fish in a separate pond.
2.3 Treatment:
– Increase the salt concentration in koi ponds/tanks by 0.5% per day, maintaining the water temperature at 27°C.
– Dissolve 3-5 drops of methylene blue in 20 liters of water and change water daily once.
3. Red Dot Disease in Koi Fish:
3.1. Causes:
The cause of red spot disease is due to Aeromonas Hydrophylla or Pseudomonas bacteria. Koi fish often get sick around March-April or August-September lunar calendar.
3.2. Symptoms:
Symptoms of red spot disease in Koi fish: red hemorrhagic spots appear on the body, scales fall off in patches. Additionally, the Koi fish have symptoms such as refusal to eat, lethargy. When the disease is severe, fins may tear or detach. Some may develop ulcers, pus, fungal infections, bulging eyes with hemorrhage, pale gills…
3.3. Treatment methods:
– If raising fish in a pond: change the water in the pond, add calcium powder dissolved in water, spread evenly throughout the pond at a dosage of 2 kg/100m²/2 weeks to raise the pH level in the water environment.
– If raising fish in a small pond, you can apply a salt-shock method with tetracycline (1 cubic meter of water = 1 packet of tetracycline + 1kg of salt). Apply the salt-shock continuously for 3 days.
4Parasite Diseases – Skin Flukes and Gill Flukes
4.1. Causes:
Parasite diseases, including skin flukes and gill flukes, in koi fish occur due to poor water quality in fish ponds/tanks, low oxygen levels in the tank, and high organic matter concentration.
4.2. Symptoms:
Fish suffering from skin flukes and gill flukes may exhibit several symptoms, such as: abnormal swimming posture (swaying), frequent scraping against the bottom or sides of the tank/pond, twitching due to itching, and jumping out of the water. Parasites causing blood loss lead to lesions and gill damage; if untreated promptly, fish may die.
4.3. Treatment Methods:
To treat skin fluke and tapeworm, you can use Koi fish feed Praziquantel. Soak praziquantel at a dosage of 2g/1m3, apply 2 doses 2 days apart, please note: change water by 20% before application.
