How To Care For Koi Carp

Koi are one of the most beautiful and rewarding fish you can keep. They’re colourful, full of personality, and can live for decades with the right care. Don’t worry — looking after them isn’t as hard as it sounds. Here’s everything you need to know, made simple.


🌊 The Right Pond


  • Size matters: Koi grow big — often 60–90cm! A proper koi pond should start at about 2,500 litres, but bigger is always better.
  • Depth: At least 3 feet (90cm) so they stay safe through hot summers and cold winters.
  • Filtration: Koi are messy eaters. A good filter keeps the water clean and the fish happy.



Tip: If you can see the bottom of your pond, your koi can see you too!


💧 Water Quality Made Easy

Think of clean water as fresh air for koi. Test your water regularly — it’s simple and takes minutes.


  • pH: Aim for 7–8.5
  • Ammonia & Nitrite: Always 0
  • Nitrate: Keep low with water changes and plants
  • Oxygen: Add an air pump or waterfall — koi love moving water



🍽️ Feeding Your Koi


  • Summer: High-protein koi pellets = growth and colour.
  • Spring/Autumn: Switch to wheatgerm food that’s easier to digest.
  • Winter: When water drops below 8°C, koi rest and stop eating. That’s normal.



Golden rule: Feed little and often, only what they’ll eat in 3–5 minutes.


🐠 Koi Friends & Behaviour

Koi are social and love company. Keep them in groups, and they’ll often come up to greet you — especially at feeding time.


Good pond mates: goldfish, orfe, tench.

Not so good: tiny fish that might get out-competed for food.


🛡️ Staying Healthy


  • Watch daily: are they swimming normally, fins open, colours bright?
  • Quarantine any new fish before adding to your pond.
  • Net your pond if herons are about — koi are curious, but herons are hungry!



❄️ Winter Care


  • Koi survive winter outdoors if your pond is deep enough.
  • Keep a small hole in the ice with an air pump or pond heater — this lets gases escape.
  • No feeding under 6–8°C — they’re in hibernation mode.



🎉 Why People Love Koi

Koi aren’t “just fish.” They recognise their keepers, can be hand-fed, and every pattern is unique. Some people treat them like living jewels… others just love the splashes and colour in their garden.


📍 Need more advice?

Come and see us at Wakeykoi & Aquatics, Himley (Sandiacre Garden Centre). We’ll help you pick the perfect koi and show you exactly how to keep them thriving.