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Acclimatisation tips: Settling new koi after delivery
When koi arrive by courier, the way you handle them in the first few hours makes all the difference. They’ve travelled for a full day, sometimes longer, and while the bags keep them oxygenated, the stress is real. Rushing this stage or skipping key steps can lead to health problems that spread through your whole pond. In this guide, we’ll walk you through the process we use when settling new koi, from preparation before delivery to the final checks before they join your pond.
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Prepare before delivery
The work starts before the box even arrives. You want everything ready so the fish can settle without delay. A few things we always keep on hand:
Colombo Fish Protect - This isn’t just a dechlorinator, it also contains ingredients that stimulate the koi’s mucus layer, which helps reduce stress as they adjust, and protect against disease.
Salt - Used at 0.3% in a pond or holding tank, it supports osmoregulation and takes some of the strain off the koi during acclimation.
Colombo Alparex - A must-have. We use it every time fish arrive from Japan into the UK. It helps koi settle quickly and has never let us down.
Alongside products, make sure you’ve got a clean bowl, a sock net, and a microscope with slides if you plan to check for parasites. Keep the environment calm with no loud noise and no rushing about. The smoother this stage is, the easier everything that follows will be.
Want to know more about how with ship your koi?
Visit our koi delivery page to find out more about how we prepare, pack, and ship your koi so you can feel confident when ordering from us.
First steps on arrival
When the courier drops off your koi, put the box down gently. Don’t shake it about or rush to open it. The fish have already been through enough.
Open the box and check the bags. The koi are fully oxygenated and can last up to 48 hours like this, so there’s no need to panic. What they need most is rest.
Keep the bags closed and let the koi settle. We recommend leaving them for at least an hour. If you’ve got time, two to four hours is even better. The only reason to cut that time short is if the koi looks stressed in the bag, in that case, you’ll need to move on to acclimation sooner.
This resting stage is about giving them a breather after the journey. Rushing them straight into a new pond is where most people go wrong.
The acclimation process
After the koi have rested, it’s time to start acclimating them. The aim here is to reduce any shock from temperature or water chemistry changes.
Float the bag - Place the sealed bag in your pond or holding tank. This balances out the temperature slowly.
Add pond water - Before moving the koi, take them out of the bag into a bowl. Add a small scoop of your pond water into the bowl. This helps the fish adjust to your water without a sudden shock.
Never add bag water to your pond - The water they travelled in may still carry waste. Keep it out of your system.
Take your time here. A slow and gentle acclimation is always safer than rushing.
Products that help reduce stress
As mentioned above, here are a few products make a big difference when settling new koi:
Colombo Fish Protect - Works as a dechlorinator and contains ingredients which help calm koi and supports their slime coat.
Salt at 0.3% - Some people avoid it, but we’ve seen time and again how much it helps koi adjust to a new environment.
Colombo Alparex - This one’s non-negotiable for us. Every shipment that comes in from Japan, we use Alparex. It helps the koi settle and keeps stress levels down.
We import thousands of koi every year, and this mix of salt and Alparex has always been reliable. If you’re serious about koi, these should always be in your cupboard.
Transferring koi to the pond
When the koi are ready to move, do it with care. Use a sock net to lift the fish from the bowl, not your hands. This keeps them safe and supported.
Add a small scoop of pond water into the sock as you go. This helps the fish adjust on the way over, making the change less of a shock.
The key rule here is simple: never put shipping water in your pond. That water may container waste. Always move the koi directly and only use your own pond water for the final acclimation.
Once they’re in, release them gently and give them time to settle. No feeding, no fuss. Just let them adjust.
Health checks on arrival
Every new koi should be checked before joining your collection. Even from trusted dealers, it’s your responsibility to protect your pond.
The best way is to carry out a scrape. This means taking a small mucus sample from the koi (usually from just behind the head down towards the tail) and checking it under a microscope. Place it on a glass slide and look for parasites.
The usual culprits to watch out for are flukes, Trichodina, or Costia. They’re not always present, but when they are, you want to catch them before the koi goes into your pond.
Think of this step as insurance. If the scrape is clean, you’ve got peace of mind. If not, you can treat straight away without risking your whole collection.
When to contact your dealer
If you find parasites or any problems during your checks, don’t guess at treatment. Get in touch with the dealer straight away. A good dealer will give you advice on what to use and how to handle it.
Sometimes it’s a quick fix, sometimes it needs a proper treatment plan. Either way, dealing with it early stops things from getting worse.
Remember, koi are livestock. Even with the best care in preparation and shipping, issues can appear. What matters is how quickly and calmly you deal with them.
Final thoughts
Settling new koi after delivery isn’t complicated, but it does take patience. Give them time to rest, acclimate them slowly, and use the right products to reduce stress. Never add shipping water to your pond and always carry out a health scrape.
These steps protect both the new fish and your existing collection. Stick to the basics and you’ll keep your koi safe and healthy from day one.