Common koi health problems
1. Parasites
- White spot (ich): tiny salt-like spots, rubbing/flashing against objects, irritation
- Gill or skin flukes: flashing, excess mucus, clamped fins
- Anchor worms and fish lice: visible parasites attached to the fish
- Costia: Excess mucus production (slimy appearance), Flashing/rubbing against pond surfaces, Clamped fins, Lethargy and hiding, Loss of appetite, Sitting on the bottom, Gasping or increased breathing rate (when gills are affected), Grey/blue film on the skin in advanced cases
- Trichodina: Flashing (rubbing against pond surfaces), Clamped fins, Excess mucus/slimy skin, Flicking or shaking the body, Reduced appetite, Lethargy, Sitting on the bottom, Increased breathing rate if gills are affected
2. Bacterial infections
- Ulcers or red sores
- Fin rot
- Mouth damage
- Red streaking in fins
These often become problems after injury, stress, or poor water conditions
3. Viral diseases
- Koi herpesvirus (KHV): a serious disease that can cause rapid deaths and requires laboratory testing for confirmation.
- Carp pox: waxy white growths on skin; often less serious and may improve with warmer water.
- Koi Sleep Disease (CEV): is a viral disease caused by carp edema virus (CEV)
4. Koi Conditions
- Dropsy is not a single disease; it is a visible condition where fluid accumulates inside the fish, causing swelling (Pine coning)
- Brown blood disease; is a common term for nitrite poisoning. It occurs when high levels of nitrite in the water enter the fish's bloodstream, turning the blood a chocolate-brown color and destroying its ability to carry oxygen, which can cause the fish to suffocate
