Understanding Koi Behaviour (Guide To Their Actions)

Koi Behaviour Understanding Their Actions in Pond

As koi enthusiasts, we often find ourselves captivated by the unique behaviours of these beautiful fish. However, it’s crucial to understand that certain actions may indicate underlying issues or concerns in your pond. We’ll explore some unusual koi behaviours and what they could signify, along with quick tips on how to address them effectively.

Gasping at the Surface

If you observe your koi gasping at the water’s surface, it’s a sign that they may be struggling to find sufficient oxygen. This can occur during hot summer nights when oxygen levels deplete, especially if your pond has abundant plants and floating debris. To address this, consider adding a spitter or fountain to break the surface tension and introduce oxygen. In emergencies, a small sump pump or aeration stone can also provide temporary relief.

Loss of Appetite

When your typically voracious koi show little interest in food and appear listless, it’s essential to investigate potential causes such as nitrogen or ammonia issues. Testing the water parameters can help identify the problem, and appropriate products can be used to rectify the situation.

Flashing or Scratching

Observing your koi repeatedly rubbing or flashing against rocks or other surfaces could indicate the presence of parasites. While occasional scratching is normal, excessive and frequent flashing is cause for concern. Treating the affected fish with medications can help eradicate the parasites and restore their well-being.

Ramming or Bumping Behaviour

During mating season, male koi may exhibit aggressive behaviour, such as ramming into other fish. This behaviour is driven by their instinct to find a female carrying eggs. While it may appear aggressive, it is a natural behaviour associated with breeding. However, if smaller koi are being injured, providing hiding spots like milk cartons or crates in the pond can offer them protection.


Understanding koi behaviour is essential for maintaining a healthy and harmonious pond environment. By recognizing the signs and taking appropriate actions, you can address potential issues promptly and ensure the well-being of your cherished koi. Remember, a vigilant eye and proactive care will go a long way in keeping your pond thriving and your fish happy.

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