Whether you’ve been keeping koi fish for years or you’re just starting your journey, adding new koi fish to your pond is always exciting. But while it’s fun to pick out colorful and eye-catching fish, it’s also important to know where they’re coming from and how to make sure they’re healthy.
This easy-to-follow guide will help you understand what to look for when buying koi, how to choose a trustworthy seller, and how to safely bring your new fish home.
1. Look Carefully at the Fish Before You Buy
The first thing you should always do when shopping for koi is take a good look at them. Healthy koi are active and alert. When food is offered, they should swim toward the front of the tank or pond, showing interest and energy. This is a sign that they feel well and are used to their environment.
Be cautious if you see koi that:
- Stay in one corner of the tank or pond
- Show no interest in food
- Have cloudy eyes, white spots, or damaged fins
- Appear to be breathing hard or moving in an unusual way
These signs could mean the fish are sick or under stress. Even if just a few look unwell, it’s better to walk away and find a healthier place to buy your koi.
2. Check the Conditions at the Seller’s Location
When you visit a koi seller, look at the whole area—not just one fish. A clean space with healthy-looking fish in every tank is a good sign. On the other hand, if several koi look sick or the tanks have dirty water, that’s a red flag.
Watch out for:
- Bad smells (a strong, fishy or rotten odor)
- Green, cloudy, or foamy water
- Tanks that are too crowded
- Dead or dying fish in the tanks
These problems may show that the dealer isn’t taking proper care of the koi. Poor water quality and crowded tanks can quickly lead to disease that could spread to your pond at home.
3. Ask About Quarantine Practices
Any good koi seller should have a proper quarantine system in place. This means they keep new fish in a separate area for at least four to six weeks before selling them. This break allows the fish to recover from travel stress, adjust to local water conditions, and show any hidden signs of illness.
Don’t be afraid to ask questions like:
- “Do you quarantine new koi?”
- “How long do you keep them separate?”
- “Do you check for parasites or disease?”
- “Do you use any special methods to prevent illness, like heat treatments?”
If the seller is careful and open about their process, that’s a great sign they care about the health of the fish they sell.
4. Talk to the Seller and Ask the Right Questions
Good sellers are happy to share their knowledge and answer your questions. Here are a few things you might ask:
- Where do your koi come from? (Imported or local?)
- How long have they been in your tanks?
- What kind of food are they used to?
- What temperature is your water kept at?
You can also ask if they check for Koi Herpes Virus (KHV), a serious illness that spreads easily. Some breeders use heat ramping—a method of slowly raising water temperature—to detect signs of KHV early.
The more open and informed the seller is, the more confident you can feel about buying from them.
5. Be Respectful and Build Trust with Dealers
When visiting a koi dealer, it’s important to be polite and respectful. Don’t ask them to catch fish out of the water unless you’re serious about buying. It stresses the koi, and it takes time and effort to do it safely.
If you’re interested in a fish, have a rough price range in mind and talk to the seller about it before asking them to net the fish. Building a good relationship with your local dealer can be helpful in the long run. They can offer advice, recommend supplies, and help if you ever have health concerns about your koi.
6. Watch the Fish Swim Before You Choose
Before making your final choice, take a few minutes to watch the koi in the tank or pond. Look at how they swim—do they glide smoothly, or do they struggle? A healthy koi has balanced fins, a strong body, and moves confidently through the water.
Also, check for:
- Even coloring and smooth skin
- Straight backs (no bending or hunching)
- Good body shape—not too thin or bloated
Taking your time helps you choose a fish that you’ll enjoy watching for many years to come.
7. How to Safely Bring Koi Home
After you’ve made your pick, it’s important to move your new koi to your pond in a safe way. Here’s how:
- Float the Bag: Place the bag (with the koi still inside) on top of your pond for 15–20 minutes to let the temperature adjust slowly.
- Mix the Water: Add a small amount of pond water into the bag every few minutes. This helps your koi get used to the new water conditions.
- Release the Fish: After about 30 minutes, gently guide the koi out of the bag and into the pond. Try not to pour the bag water into your pond, especially if you don’t know the dealer’s water quality.
8. Keep New Koi in Quarantine at Home
If you already have koi in your pond, it’s a smart idea to keep new ones in a separate tank for a couple of weeks. This gives you time to make sure they’re healthy and won’t pass anything on to your existing fish. After two to four weeks with no signs of illness, you can move them into the main pond.
Final Thoughts: Be a Responsible Koi Buyer
Buying koi is more than just picking the prettiest fish. It’s about caring for their health and making sure your pond stays clean and happy. When you take the time to choose healthy fish, ask smart questions, and introduce them to your pond the right way, you’ll enjoy the beauty of your koi for many years.
Koi are peaceful, long-living fish that bring calm and color to any outdoor space. With the right care and attention, your koi pond will become a joyful part of your life.
