KOI FISH NISHIKIGOI

Koi Disease Diagnosis and Treatment

Koi and goldfish are typically very hardy, robust fish and don’t often once become sick once they have settled into the pond. Occasionally, goldfish and koi disease occurs in ponds as fish fall prey to parasitic, bacterial or fungal attacks. The causes of fish diseases are varied and can range from a sudden drop in water temperature, predator attacks and spawning to name a few. No matter what the cause of the disease, one thing remains constant – the sooner you recognize and begin to treat the problem …the more likely you will be successful treating the disease. So how do you know if you have a sick fish? Sometimes the signs that a fish is sick are very subtle, such as one fish segregating itself away from other fish, or maybe not eating very much. As time passes and the disease gets worse, the symptoms become more obvious and may spread to other fish.

The picture below shows a Trichodina parasite magnified under a microscope

Causes of Koi Disease

Koi and goldfish are very hardy, resilient fish. In most cases, stress is the cause of most diseases in fish. Stress? Yes, but the stress that causes fish to get sick is usually in the form of poor water quality, overcrowding or other environmental factors. If koi or goldfish are kept in ideal conditions, they rarely get sick because they are able to fight off possible attacks from parasites or bacteria.

Stress
Poor water quality
Introducing sick fish to your pond
Spawning
Overcrowding
Contamination (pesticides, fertilizer etc.)

Signs of Koi Disease

There are several ‘early warning signs’ that indicate that your fish may be under attack from parasites or bacteria. The first sign of a problem usually starts with one fish that segregates itself from the rest of the school, often hanging listlessly near the surface of the water. If this fish doesn’t eat, it’s a sure sign that something isn’t right. Recognizing the first signs of disease is important because it can be controlled much more easily if it is caught early. Depending on the situation, disease can spread to many or all fish in the pond relatively quickly. It’s always a good idea to take count of your fish at feeding time and also take a close look them while they are close to the surface.

Not eating
Fish segregating itself from others
Fins clamped close to the body
Fish acting listless or lethargic
Gasping at surface of pond
Fish Sitting on bottom
Hanging near surface or near waterfall
Red streaks in fins
Ulcers (red sores)
White spots
Ragged fins
Fluffy cotton-like tufts

Koi Disease Identification

The only way to properly identify parasites on fish is take a skin scrape and look at it under a microscope. Most people don’t have microscopes, so the next best thing is to take a close look at your fish and try to compare the symptoms to the diagram below.

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