Sometimes, even when we work hard to keep our koi fish happy and healthy, sickness can strike. Whether it be a stray parasite, a drastic drop in temperature, a mysterious virus, or some questionable pond water, we’re here to expose some of the most common koi fish diseases.

PREVENTATIVE CARE

As a rule of thumb, the best way to inspect your koi is during feedings. While you’re spending some quality time together, watch your koi fish as they come to the surface. Identifying any odd behavior or appearances is the best way to check up on your koi’s health.

The best way you can care for your koi fish’s health is by keeping up with pond maintenance. With regular water testing, filtration, and proper pond care, you’ll reduce your koi’s stress and keep their immune systems healthy.

 If your koi fish do happen to fall ill, medications and treatment are available at your local pet supply store or koi breeder. If you’re unsure of the severity or diagnosis of the disease, contact an aquatic veterinarian.

Disease happens in the event of a decreased immunity and the presence of a pathogen. It can also be caused by an imbalance in water levels. If your koi seem to be under the weather, double check on water levels in the pond before taking further action. Here are some common ailments in the koi pond:

LEECHES

Leeches are a parasite that latch on to a koi and feed off their blood. They can be introduced to a pond via pond plants. Leeches can be easily spotted by a naked eye and they don’t usually cause serious harm to a koi. In young koi, an abundance of leeches may cause anemia. The cuts they leave on koi scales also leave room for bacterial infection.

BACTERIAL GILL DISEASE

If your koi seem sluggish, inactive, and pale, and is slimy to the touch, they may be suffering from bacterial gill disease. It is caused by bacteria and common, especially in overcrowded ponds. The disease may also leave white patches of dead tissue on the gills. Incorrect water levels and a high level of organic material in the ponds also cause bacterial gill disease. Fortunately, it is easily treated with antibiotics.

ANCHOR WORMS

These pesky crustaceans are all too common in koi ponds. They’re inactive during the winter, but when spring temperatures reach 50˚F, anchor worms reappear. They look like brown or black strings attached to a koi’s body and are usually around a quarter to a half inch long. When they’re young they look like white dots. If your koi fish seem extra jumpy all of a sudden, they made have anchor worms. Buy a water treatment fast to avoid infection setting in the wounds they leave on koi fish.

SAPROLEGNIASIS

This fungal infection appears in white streaks on a koi’s scales. It’s fairly common and appears cotton-like to the eye. While relatively harmless and easy to treat in early stages, this fungus is dangerous once it infects a koi’s gills, making it difficult to breathe. This fungal infection often appears when a koi is moved or in addition to other diseases and can be treated by commercial medication.

FISH LICE

Fish lice, also known as Argulus, is a crustacaen that crawls about a koi’s body. It has a flat, scale-like appearance and leave reddish spots of a koi’s body. Fish lice can be see with the naked eye and are identified easily by observing them move about a koi’s body. If your koi appears to be breathing laboriously, they may have fish lice in their gills. Also watch for fish lice eggs laid on pond plants. Treatment is possible with commercial medication.

Here’s to keeping your koi fish happy and healthy! Have any tips for treating koi fish diseases? Let us know via the contact form!