So, you’ve seen them—those shimmering jewels gliding through clear water, their colors dancing in the sunlight—and you’ve decided: I want koi. Excellent choice! But before you rush to your nearest pond shop or click “add to cart” online, take a breath. Buying koi isn’t like picking out goldfish at the fair. These fish are living art pieces, long-term companions, and ecosystem partners. Here’s your entertaining (and practical) guide to everything you should know before you buy koi.
1. Know Your “Why”
Ask yourself: what’s your goal? Do you want a peaceful backyard pond with a few friendly koi, or are you aiming to build a show-quality collection worthy of competition? Your answer shapes everything—from pond size to budget to the types of koi you’ll choose.
Fun fact: Some koi hobbyists treat their ponds like art galleries, swapping fish and patterns like collectors trade paintings. Others just want calm water, sunlight, and serenity. Both are perfectly valid.
2. Check Your Pond First—Not the Fish
The biggest beginner mistake? Buying koi before your pond is ready. Your fish deserve clean, cycled water, not a half-dug hole and a dream. Before shopping, make sure your pond:
- Is at least 2 to 3 feet deep (deeper is better).
- Has a filtration system that can handle twice your pond’s volume.
- Includes aeration (air stones or waterfalls).
- Has been running for a few weeks to allow beneficial bacteria to establish.
In short: build the house before you buy the tenants!
3. Set a Realistic Budget
Koi come in all price ranges—from $20 “pond-grade” beauties to $5,000 show champions. For beginners, there’s no need to go big right away. Start with younger, affordable koi. They’re easier to acclimate, grow quickly, and let you learn without stressing about a fortune swimming in circles.
Remember, the pond setup (liner, pump, filter, food, test kits) usually costs more than the fish themselves. But once it’s built, the hard part’s done—and your koi will thrive.
4. Choose a Reputable Source
Not all koi sellers are created equal. Look for breeders or dealers who:
- Quarantine their new fish before selling.
- Provide clear information on each koi’s variety, age, and health.
- Let you observe their setup—clean water, active fish, no cloudy tanks.
Be cautious of “bargain bins” or mystery koi bags online. Healthy koi are active, alert, and have bright eyes and smooth scales. A sluggish koi sitting at the bottom of the tank? Walk away. That’s a red flag (and not the pretty kind).
5. Pick Varieties You Love
Koi come in over a hundred recognized varieties, from pure white Platinum Ogon to fiery red-and-white Kohaku to the dramatic black and red Showa. There’s no right or wrong choice—just what catches your eye and fits your pond’s aesthetic.
Pro tip: Start with different color types so your pond looks lively and balanced. It’s like designing your own living art exhibit!
6. Understand Growth and Space Needs
Those cute little koi you buy at 4 inches? Give them a few years, and they could hit 24 inches or more. Always plan for their adult size, not their baby size. Overcrowding leads to stress, disease, and murky water.
A good rule of thumb: one koi per 250–500 gallons of water. Fewer fish = better health, better water, and bigger growth.
7. Learn Basic Water Care
Healthy koi start with healthy water. Before bringing your new pets home, get familiar with water testing and maintenance. You’ll want to check levels for ammonia, nitrite, nitrate, pH, and KH. It might sound technical, but once you get the hang of it, it’s as routine as checking your coffee maker in the morning.
And don’t worry—you don’t need to be a chemist. You just need to keep things stable and clean. The koi will do the rest.
8. Have a Quarantine Plan
Even healthy koi can carry parasites or bacteria that don’t show symptoms right away. A simple quarantine tank for new arrivals is your best defense. Keep new koi isolated for two to three weeks, observe their behavior, and treat for common parasites if needed before introducing them to your main pond.
Think of it as a koi spa retreat before they join the big party.
9. Think Long-Term
Koi aren’t a seasonal hobby—they’re a long-term relationship. With proper care, these fish can live 30 to 50 years (some even over a century!). That means your koi could outlive your dog, your car, and maybe your Wi-Fi router. They’re truly family members in scale form.
Make sure you’re ready for that commitment—because once you start, koi keeping has a way of becoming a lifelong passion.
10. Enjoy the Process
Don’t rush it. The fun of koi keeping isn’t just in the fish—it’s in building the pond, tweaking the setup, and learning as you go. Every pond tells a story, and every koi adds a new chapter. Before you know it, you’ll be the one giving advice to new hobbyists (and busting a few myths yourself).
In short: prepare your pond, do your homework, and choose fish that make you smile. The moment you see your first koi glide across the water, you’ll know it was all worth it.