7 Simple Tips for Maintaining a Healthy Koi Pond

Ginny Bartolone
Written by Ginny Bartolone
Updated February 22, 2022
 Backyard with a big koi pond
Photo: cjmckendry / E+ / Getty Images

There's no need to be coy about your interest in koi pond care

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Combine the gentle sounds of flowing water with a visit from a brightly colored koi, and you have yourself a true backyard haven of calm. Caring for a koi pond is not a passive hobby or low-maintenance lawn feature, but it can make a huge impact on the look and ambiance of your water feature. If you've recently moved into a home with a koi pond or had one installed by a local pond expert, here are some basic tips to get you started on the art of koi pond care.

1. Create a Koi Pond Care Schedule

Let's start off by reiterating that maintaining a koi pond takes time and a lot of TLC. Koi pond owners even enter competitions to show off their ponds’ stellar maintenance and development. If you build a dependable schedule and know the elements of a healthy koi pond, this can become an excellent source of stress relief.

This said, you will need to set time aside to feed your fish about once a day, test the quality of your koi pond water—more on this below—and perform seasonal maintenance.

2. Get to Know Your Fish

Closeup of koi fish in a pond
Photo:IssarawatTattong / Moment / Getty Images

There are many species of koi to choose from with differing patterns, colors, scaling, and size. These impressive creatures can grow from just a few inches to 3 feet long. Koi are freshwater fish that typically require at least 50 to 100 gallons of water each depending on their grown size. Koi also love company, so your pond will likely have at least two of the same species or a combination of koi and goldfish.

When introducing a new fish to your koi pond, speak with your pet store or distributor to follow proper quarantine and introduction tips to avoid shocking your fish.

3. Ensure Proper Installation

The first step to excellent koi pond care is excellent pond installation. While we'll assume for this guide that you already have a pond installed, it's important to know the parts of your pond for proper care. Let's take a look:

  • Pond liner: Designer line the bottom of a koi point with rubber, PVC, or concrete to keep water from leaking.

  • Filters and Skimmers: These either sit at the waterline, beneath the water surface, or on your waterfall to clean bacteria and debris.

  • Water pump: Pumps are crucial to aerating the water for your koi. You'll find a large variety of large pumps to small aerators that sit at the bottom of the water.

  • Rocks and gravel: These keep the liner in place during storms and provide a spot for healthy bacteria growth. Be wary of decorative rocks that may contain unhealthy chemicals.

  • Plants: The right plant life adds nutrients, balances oxygen, and even offers a food source to your fish.

  • Pipes: Piping connects the filters, drains, and pumps and removes overflow water during a storm.

Choosing the right model or variety of each part comes down to where you live, the placement of your pond, and even what your koi prefer. Read all user guides carefully to ensure you purchase the right model.

4. Manage Water Filtration and Aeration

Your koi pond is a living, breathing ecosystem that requires a bit of balancing in the world of your backyard. Your pump, filter, and plants will do a lot to keep your koi water clean, but not without your help. Too much heat, algae, or unwanted chemicals can be harmful to the water's oxygen levels, pH levels, and, therefore, the health of your koi.

Test the quality of your koi water with a testing strip one or two times a week for its pH, oxygen levels, ammonia, nitrates, lead, copper, iron, and zinc. These levels will also change after a large storm and after switching out part of the water each week.

5. Manage Your Koi Pond Plant Life

Pink water lily and koi fish in a pond
Photo: Martin Wahlborg / iStock / Getty Images Plus

Plants are a wonderful part of your koi ecosystem, contributing to oxygen levels, cutting down dangerous nutrient levels, and welcoming other pond creatures like frogs and snails. Your koi will like to snack on many common pond plants as well. Favorites include water lilies, water lotuses, water lettuce, and eelgrass.

Keep in mind that you must play the part of the gardener as well. Overgrowth or decomposed plants can throw off the balance of your pond when not properly pruned.

6. Avoid Overfeeding

One of the most common rookie mistakes when growing a koi pond is overfeeding your fish. There's no hard-and-fast rule about how much and how often to feed your koi. The amount depends on the plants in the water, the time of year, and the size and type of your koi.

Overfeeding your koi can not only damage their health in some cases—such as in the winter when they may not completely digest food—but also add too much bacteria to the water.

Koi will eat one to four times a day in the peak of summer and just one to two times a week in the colder months. If you live in a cold region, many koi do not eat throughout the winter when the water dips below 40 degrees.

7. Know Your Seasonal Koi Pond Care

Remember when we suggested making a koi pond care schedule? You can create a year-round calendar as well. Much like caring for your garden, koi and their surrounding plant life change with the seasons.

Summer

Summer can warm up your water temperature and damage your fish and plants. You may need to change more of your water during the summer and spend more time managing algae or unwanted bacteria.

Fall

The autumn brings falling leaves and debris that can break down into your water and throw off bacteria and algae levels as well. Be sure to prune your koi pond plants based on their instructions in the fall. You may even need to remove some potted, submerged plants for the winter.

Winter

And while it may seem shocking, your koi will enter into a type of hibernation in the winter, requiring little to no feeding. They can handle the freezing temperatures of your pond but still need water to come from the surface. Purchase a floating de-icer if you live in an area with temperatures consistently below freezing.

Spring

Much like a garden, slowly begin to feed your koi as they come out of hibernation and the water warms up. This is also a great time to perform a spring cleaning of your pond. Replace a larger percentage of your water, prune debris from dead plants, and ensure you have clean filters, pumps, and drains.

Koi ponds can become a lifelong hobby if they bring you joy, but they do come with some trial and error. Work with an experienced local pond expert when just getting started, head on vacation, or simply need a bit of advice.

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