Top 5 Possible Causes of Dragon Fish Sudden Death

Why Do Koi Fish Suddenly Die?

One: Accidental Incidents

Accidents like power outages, hypothermia, or hunger can lead to sudden deaths in koi fish. However, these situations are often preventable. If owners choose to keep koi, they must master the basics of koi care. If such issues arise, it may indicate that the owner is not wellsuited for fishkeeping.

Two: High Levels of Molecular Ammonia

Koi fish are generally resistant to most harmful factors, but they are highly sensitive to molecular ammonia, especially in red koi. When the level of molecular ammonia in the water exceeds 0.02 mg/L, koi may show symptoms like dullness, stiff whiskers, increased mucus on the gills, head shaking, pale mucous membranes, and decreased appetite. In severe cases, they may experience fin bleeding, gill adhesion, swollen anal area, internal bleeding, and nervous system damage. The period from onset to death typically ranges from 10 to 30 days, but if owners are negligent and fail to notice these signs, koi may suddenly die as the condition worsens.

Three: High Levels of Nitrites

While koi are less sensitive to nitrites than molecular ammonia, excessive levels in the water can cause the fish to have dark red gills and difficulty breathing. This effect is similar to carbon monoxide poisoning in humans. Nitrites bind with koi's hemoglobin, inhibiting oxygen transport, which can ultimately lead to oxygen deprivation and death.

Four: Head and Lateral Line Erosion Disease

Head and lateral line erosion is a highly fatal disease in koi. Affected fish develop small holes or boils on their heads. The direct cause is the decomposition of the head's calcified cartilage, often due to vitamin deficiencies, flagellate infections, or deficiencies in calcium and phosphorus. If treated promptly, these diseases are usually curable. However, if owners fail to detect the illness early, severe cases can lead to the fish's death.

Five: Overuse of Medications

Medication overuse is a common cause of sudden koi deaths. Many fish medications available on the market contain nitrofuran derivatives, which are effective for fish sterilization. Furazolidone and nitrofurazone are commonly used in koi. However, if owners do not control the dosage properly, excessive medication can lead to liver and gallbladder damage in koi. Moreover, these broadspectrum, strong antibiotics can easily damage the aquarium's nitrification system, causing a sharp increase in ammonia and nitrites in the water, posing a fatal threat to the fish.

To prevent high levels of molecular ammonia in the water, owners should ensure a wellestablished filtration system in the aquarium. Since ammonia in the aquarium is mostly produced by fish waste and food debris, a good filtration system can convert these waste products into lowertoxicity nitrates, preventing high concentrations of ammonia and nitrites in the water.

These are some of the reasons why koi fish may suddenly die. Generally, if owners feed their koi properly, ensure clean and harmless food, and regularly change the water to maintain good water quality, koi are unlikely to suffer from sudden deaths.