Would you enjoy pet koi fish in a backyard pond while drinking your morning coffee? Koi keeping is a rewarding hobby.
How Many Koi Per Gallon of Water?
1. Make sure your pet koi fish have plenty of space. Koi fish require at least 250 gallons per fish to avoid crowding.
Koi are members of the carp family of fish and grow large. A healthy koi can grow up to 36” and beyond 20 pounds in weight with the good water conditions.
Keeping a pet koi fish tank at home might work temporarily for small fish (3” or less), but it’s not a viable long-term solution. Even a 110-gallon aquarium is too small for more than a 6 – 7” koi.
They are messy eaters and typical home-style aquarium filters can’t keep up with the waste large koi will produce.
2. Keep your pet koi fish out of direct sunlight. Sunlight damages their skin, making them vulnerable to disease and parasites.
The pond or tank where you keep your koi needs to be at least 4’ deep, and even deeper if you live in a cold climate with prolonged freezing temperatures causing ponds, lakes, and rivers to freeze over.
If the body of water is not large enough, the unfrozen water will not hold enough oxygen to sustain fish life. The metabolism in pet koi fish slows down in icy water temperatures and they eat much less food, but koi cannot survive without adequate oxygen in the winter months.
We recommend consulting with an aquaculture expert, and preferably someone who is a koi expert, to help you design and build the pond, filtration, water source strategy, landscape, waterscape, etc. that a good koi pond needs.
How Much Do Pet Koi Ponds Cost?
Koi keeping is expensive. Costs for an in-ground koi pond reach $25,000, or more, and a do-it-yourself above ground pond will cost more than $5,000 depending on how many supplies you have on hand and how much you need to buy.
3. It’s possible to save money by salvaging some of the supplies you may need from other sources (i.e., repurposed concrete blocks, 4 x 4 wood, bricks, pond liner, etc.).
Secondhand aquaculture items are available from another koi keeping hobbyist that is downsizing, upgrading, or getting out of the hobby altogether. And people sometimes inherit a koi pond when purchasing a new home.
A third option, a frequent choice of novices, includes buying cheap supplies from a discount source. It’s not always the price of the supplies that causes the challenges. It’s often the lack of handholding and support after the sale when you have additional questions or run into problems. Paying for quality up front often includes support after the sale and an ongoing source of information as you proceed in your koi keeping endeavors.
Scrimping on supplies may sound good at first, but overall, we predict you will come out ahead by hiring an experienced aquaculture professional to guide you in the beginning.
Carpenters have a saying – Measure twice, cut once. Similar advice about keeping pet koi – Buy good equipment once, and your fish might not die.
Is Water Quality Important for Pet Koi Fish?
Outside of a correctly sized pond to start, maintain excellent water quality is vital.
4. Provide pet koi fish with clean, filtered water. Tap water sometimes contains chemicals that can harm your koi. A spring or well can sometimes work well, but please have your water professionally evaluated before introducing new koi to the pond.
The koi pond needs proper cycling to ensure adequate beneficial bacteria develop to keep the nitrates, nitrates, and ammonia levels at or near zero in your pond.
Become familiar with the quantity of water needed to sustain a koi pond if it’s not naturally fed by a spring or stream. Talk to other nearby koi pond aficionados to understand the rise in your water bills as you provide new sources of water for your fish on a regular basis.
In warm climates it’s common to lose 100 gallons, or more each day to evaporation, depending on the size of your koi pond. That lost water needs replenishment daily.
As an example, if your pet koi fish’s pond is losing 75 gallons of water daily, you will need to add 525 gallons of new water per week, 2,000+ gallons per month, and 26,000 gallons annually to your pond just to keep it full. You will also need to do regular water changes weekly, bi-weekly, or monthly based on water conditions.
We highly recommend that new and intermediate fish keepers join a local aquaculture club or garden club that specializes in koi and goldfish pond construction and maintenance.
If a club is not available, contact and consult with local landscaping companies who offer pond building services. There are too many variables to consider when building a koi pond and it requires someone with experience to help guide you.
A quick web search for koi pond calculator will help determine the minimum appropriate size needed in accordance with the number of koi you plan to keep. As an example, a 1,000-gallon pond will only support 3 – 4 large Japanese koi.
How Often Should I Feed Pet Koi Fish?
5. Plan to feed your koi twice daily (or more as needed or advised by your koi breeder / supplier). Fish need food just like humans do. Feeding them once a day isn’t usually enough.
Overfeeding your koi is another risk to look out for. Uneaten food creates debris and detritus that contributes to poor water quality. The amount of fish food consumed is determined by the size of your pet koi, the quality of the water they live in, and overall health of the koi fish.
When Should I Clean the Koi Pond?
6. Clean the pond regularly to help reduce the risk of illness and bacterial infections.
The simple answer – when it needs cleaning.
Monitor the water quality in your pond daily using a good water testing kit. Consider having your koi pond professionally monitored and maintained by a commercial aquaculture company or pond installer who offer that service. This is especially important if you have never kept koi fish before or consider yourself a beginner.
Inexperience and lack of understanding create unfavorable conditions in your pond for fish leading to illness and death.
What if My Fish Get Sick?
7. Watch for signs of illness. Look for bloated bellies, lethargy, and loss of appetite.
Consult your breeder, pond installer, or available veterinarian for help. Some illnesses are easily remedied, but others are difficult for beginners and some intermediates. Numerous variables are at play when improving fish health.
It’s difficult to read it in a book or watch an online video and completely understand what’s needed. Expertise in this area develops from professional training, apprenticeship, or from experience (i.e., trial and error). The trouble with trial and error though is that the pet koi end up paying the price and it puts a large dent in your bank account.
8. Never handle your pet koi fish if it’s not necessary. Handling them could result in injury to yourself, injury to your fish, and damage to their fins. Excessive or unnecessary koi handling stresses the fish and stress can cause illness.
9. Try to avoid buying koi from retailers known for selling unhealthy fish. If it’s unavoidable, make sure you quarantine the fish for several weeks, treat for parasites, ick, etc. before risking contamination in your main pond / tank. A sick fish can infect healthy fish in short order.
Buying via mail order or from a breeder who is willing to transport them to your pond, is a better alternative.
Where to Buy Koi Fish Near Me
Garden centers, pond builders, landscapers, and high-end ornamental fish stores sometimes offer koi for sale. We recommend asking your trusted friends who keep koi for referrals, but if none of your friends have kept a koi pond, you can ask for help via online koi keeping forums.
Choosing your koi seller is a serious decision because a few fish can cost you several thousand dollars depending on their size, age, color, patterns, etc.
Consider asking your koi supplier if they have baby koi fish for sale. Sometimes this can be a more affordable way to purchase koi. You would not have full size koi, but would have the experience from growing the smaller fish into full size specimens.
If you decide to buy PetSmart koi fish, be certain to quarantine them for several months before adding them to your new koi pond.
Koi vs Goldfish
Another popular option is starting with more affordable goldfish varieties and as your skill and confidence increase over time, you can trade out your goldfish with the more valuable pet koi fish varieties you’ve had your eye on. You may decide to just keep goldfish. Goldfish come in nice colors and patterns too.
- Koi are expensive
- Goldfish are affordable
- Koi have a long history in pond keeping
- Goldfish have a long history in pond keeping
- Koi have been selectively bred over centuries for patterns and colors
- Goldfish have been selectively bred over centuries for patterns and colors
- If you lose koi to an “accidental” event, it’s an expensive loss
- If you lose goldfish to an “accidental” event or mistake, it’s easier to absorb financially
Many koi sellers also sell goldfish. If you experience sticker shock while koi shopping, ask your seller if they have any goldfish available. Large fantail goldfish are beautiful in a backyard aquascape.
The casual observer rarely knows the difference between true koi and a goldfish. Unless your neighbor has kept koi in the past or works in the aquaculture industry, it’s unlikely they can tell.
Before you purchase pet koi fish carefully consider all the risks and what might go wrong.
Topics to consider:
- What is your budget for koi keeping?
- Do you have a pond already, or do you need to build one?
- Who will you turn to for help with your pet koi pond when it’s needed?
- Do you have proper nets?
- How will you quarantine new koi?
- How long will you keep them in quarantine?
- Do you have a temporary holding tank?
- What will you do if you can’t keep the koi in their normal pond environment?
- Can you transport them safely to a friend’s koi pond, if needed?
Keep a running list of considerations and questions you have about keeping pet koi before you build a pond and before you contemplate buying any fish.
Many enthusiasts start out by keeping a home aquarium to gain an understanding of water maintenance standards on a small scale before venturing into outdoor ponds.
If you prefer indoor aquarium fish to koi, you might find out article about keeping betta fish helpful.
And the biggest tip of all – Enjoy your wonderful fish!