Koi Pond Care for Beginners (A Hobby for Life)

Koi Ponds are a lot of work to set up and maintain, but the rewards to such a task are immense. You get a beautiful, zen pond in your yard, fun fish to care for and enjoy, and serene beauty! In this article, we will look at Koi Pond Care for Beginners, and go over the major steps needed to take care of koi ponds, and koi fish, in all four seasons.

Setting up a Koi Fish Pond

If you’re still in the exploration phase when it comes to installing a koi pond, be sure to see See Part 1 of our series, How to Set Up a Koi Pond to start with. In that article, we gave you tips to build an average sized pond of L24 x W12 x D4 feet. We covered topics such as excavation, pool lining, filtering systems, pumps, and aeration. Part 1 provided enough information to get you started. Now your pond is built and filled with water, it is time to introduce your koi to the water. Bring your dream together with this amazing, aesthetically pleasing addition to your back yard. This article on koi pond care will provide you with further tips to enhance your koi pond so you can become a seasoned koi fish pond owner. If you wish to get even more pleasure from this hobby, you could become a koi breeder and take your koi to shows. That’s for the future, though!

Koi Fish Care for Beginners

Koi fish grow rapidly and quickly can become sizable fish. As the koi mature, you should figure that each will need about 50 gallons of water in order to be comfortable in a pond. Smaller koi can be kept inside in an aquarium or holding tank, though you want to be sure they don’t outgrow the aquarium as they increase in size. Eventually, it will be time to place the koi in a pond!

Introducing Koi Fish to a Pond

There are tons of varieties of color, shape, size, and fin setup for koi fish available. Choose your fish with care, and most will want to aim for variety. You generally want to purchase smaller fish and watch them grow. Just be sure to account for their futuresize when figuring how many koi are appropriate for your pond. You can, of course, pick up koi fish at your local pet store. But you can also find many varieties of fish available online, shipped to your door quite easily. Different sizes and lots are available, and there is almost always a live-delivery guarantee. See this article if you want to learn about the meanings and legends of koi fish, and their colors.

Quarantining your Koi Fish

It’s a good idea to quarantine your fish for a time when you receive them before you introduce them to the fish pond. This is less important if you’re doing this for the first time, but if you’re introducing new fish to an already-established pond, it’s a good idea to set up a quarantine before introduction. This allows you to keep a close eye on the new fish to ensure they have no diseases.

Using a Holding Tank or Other Container to Introduce Koi Fish to a Pond

To quarantine fish, you need a suitable holding tank. This could be anything from a large tub, a large fish tank, or even a kids or pets swimming pool. It should be able to hold at least 50-gallons volume of water per 3 fish that are approximately up to 10-inches long. You can buy the professional koi holding tanks if you want to show your fish. They fold up to store away when not in use, but they are expensive.

Whatever you use, make sure it is strong enough to hold the heavy water. Should the tank collapse it will kill your precious fish. Obviously, it should have no leaks, so you can walk away and know your fish are safe. You will also need a protective cover over the top, such as a taut net. Stressed fish may try and jump out of their unknown environment.

Your holding tank does not need to be anything extravagant but it does need a cycling filter to remove the bad chemicals and a circulating water pump. Biofilters can take a few weeks to work effectively so take daily readings of the water until they function well. Ideally, the holding tank needs a lid such as a taught net covering over the top, to keep debris out. If you use a net, don’t allow it to sink into the water or hang loosely. Stressed fish may jump out of the water and you don’t want them getting tangled in a loose net.

Additional Advantages of a Holding Tank

A holding tank is a good investment because it can also act as a clinic for any future poorly fish. If you have concerns over any fish, you can use the holding tank to watch them closely and make sure they stay healthy. You’ll be able to stop any diseases from spreading to other pond fish. Fish can become stressed when in transportation. Not only is it differing water temperatures, but they know it’s not their usual territory. Give them a while to settle down. It helps if you can pop something in the tank that will float on the surface, such as real or faux Lillie leaves. This will provide something for the fish to hide under. Your holding tank will need a cycling filter to remove the natural bad bacteria. It might be better to use circulating water pump because water quality is important. Bio-filters can take a few weeks to work effectively but put them in as well. You will also need a protective cover over the top, such as the net mentioned above, or in the Buyer’s Guide. Stressed fish may try to jump out of the unknown environment. A net should be pulled taut, so the fish don’t become tangled in it. Don’t allow it to sink into the water, as you don’t want the fish getting tangled in a loose net. The net will also keep debris out.

Water Quality in the Holding Vessel

The quality of the water is vital. Use testing strips on the tank water daily is good practice. It will ensure the nitrate, ammonia, and pH levels are all healthy for your new arrivals.

Also, check the temperature is between 72-78F. Note that the lower the temperature, the less active the koi will be, and they will eat less. The higher the temperature, the more likely it will contain bad chemicals such as ammonia and less oxygen, neither of which is good for koi. Use a submersible aquarium water heater if necessary to keep within the temperature range as suggested. Never transfer koi to a pond that is less than 55F, as it may stress them even more.

To speed up recovery you can add good bacteria to help your koi settle quicker. Adding non-ionized salt to the water not only helps to reduce stress levels. It will not tackle any nitrites or parasites that might be present. Use around 3 teaspoons per gallon of water. Alternatively, you can use specialized aquarium products that ensure there is healthy water in the tank. Get your water set up and ready at least a few weeks before you introduce your koi to the tank.

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Introducing Fish to the Koi Pond Environment

1. Introduce the Fish to the Holding Tank

• Allow the plastic holding bag containing the koi to float in the new tank for at least 30-minutes. This will gently change the temperature of the bagged water so the koi acclimatize before entering the tank.
• Take the bag out of the water. Gently place the koi into a small net, allowing the water to drain away elsewhere.
• Try not to let any of the water in the bag get into the tank. Slowly dip the netted fish into the new tank. Don’t worry if they dive to the bottom of the tank, this is normal.
• Don’t feed them on day 1 unless they are swimming around happily and do not look stressed.

Your koi are now transferred and it’s time to help them settle.

2. Second Day Care

Some breeders suggest not to feed koi while in a holding tank because the food will sink and rot in the water. If you’re concerned, you can feed them a little if you wish, it won’t harm them.

If they are stressed they will not eat. This will need your own judgment. If they do not eat the food, try to carefully scoop it out with a small net if you can. Koi can go for many weeks without food and do so in the winter season when their metabolism slows down.

3. First Week Care

As mentioned, water quality is the most important issue for all koi. It would be best to change 25-30% of the water in the tank every week.

4. Second Week Care

Now your koi should be more settled and you can begin plans for moving them to the pond soon. If you already have fish in the pond, it is a good idea to put one in the holding tank. This introduces the pond’s bio-products slowly to your new fish. Don’t forget to acclimatize the pond fish to the tank by following Instruction 1. Don’t allow any pond water into the tank, only the fish.

5. Third-Fourth Week Care

Ιf all is looking good, you can transfer your fish to your koi pond after three weeks, but four is better. This time you will be placing the plastic bag containing the koi, into the pond.

Ensure the tank water temperature is similar to the pond water. Instead of taking your koi out of the bag with a net, simply open the bag on the surface so you can hold it. Wait for the koi to swim out of the bag in their own time. While you can leave the fish in the holding tank for longer than 3 weeks, don’t move them before the 3 weeks are complete.

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Fish that Can Live with Koi Fish

This series is specifically about keeping a koi fish pond, but you can put other fish with the koi as compliments! A few options for additional species are:

Goldfish

Best breed types are Comet and Shubunkin. This is an attractive fish that will adapt well to pond conditions. The only problem you may have is crossbreeding with the koi.

Golden Orfe

Also, like the koi, a cold-water fish. They like company, so keep at least three. Careful if you want to keep snails or frogs, as they will eat them if they catch them.

Barbel

Will keep the bottom of the pond clean of food, as they prefer to eat down there. Great if you have a waterfall, as they do better with flowing water.

Tench

Another bottom feeder. They also love to dig, which stirs up the gravel and helps with the bio-filtering system. Whatever you choose to compliment your koi, remember not to overstock. Calculate that every inch of every fish needs at least 10 gallons of water to move around freely. When you first put in your baby fish don’t forget to estimate based on the estimated full size of the fish. If they are happy they will grow quickly, so it’s worth taking this precaution. Now that you have your fish in the pond, it’s time to learn how to keep them healthy and content.

How to Keep a Koi Pond Clean

As with the tank water, it cannot be stressed enough how important this factor is to a healthy fish. A pond pump, or a combined pond pump and filter system, are almost always required to keep a koi pond clean. Following, are a few indicators that you need to keep a close watch upon if your koi are to thrive:

Test Readings

Regular checking of your koi pond’s chemical levels is required in order to ensure a healthy environment for your fishy friends. Here’s a quick table showing the basic targets. Below, we’ll go into detail on each of the major considerations.

Ammonia and Nitrites, Chlorine, zinc, Copper, Iron, and Lead

These should ALL ideally be ZERO. If readings for ammonia or nitrates reach 0.25 parts per million (ppm) or over, then you need to begin a 25% water change. The water is in need if more oxygen, so make sure you have plenty of aquatic plants in your pond. If you are noticing the growth of green algae, then your nitrite levels are too high and you must take action.

Nitrates

Nitrates levels in your pond should ideally be below 20ppm. Use a nitrate testing kit to check levels frequently. If you have readings of 80ppm or over, you must start to replace at least 80% of the water. Levels of 120ppm will kill your fish. Signs that nitrates have reached this dangerous level could be lethargic or floating fish or the growth of algae. Water plants are a great way to keep nitrate levels under control, but immediate action needs to be taken if they are high. High nitrates can also be a sign of overfeeding your fish, or too many fish for your pond size.

pH Levels

pH between 7-8.5. Below 7 means the water is acidic, such as when it rains. Above 8 means too much carbon dioxide is being removed, such as with the growth of algae. Keep in mind that pH levels are different during the daytime and at night. Ideally, it’s best not to use chemicals if the readings are too high or too low. Instead, make the changes in your aeration system gradually, as sudden changes could harm the fish. Adding a waterfall that runs all day and night for water movement, would help tackle pH balance. Turn up the pumps if you can, you need to get the water churning.

Oxygen Levels

Oxygen levels should be between 6-9mg/L (milligrams per liter of water). If the readings are too low, then turn up your pond air pump or fit more of them. You need to be moving the water to add more oxygen. When the temperature of the water gets higher, the oxygen levels will drop. Should your reading drop to 3-4mg/L, you may even notice your fish gasping for air on the surface. You may also find they may gather in a cluster around the moving water of the fountain.

Testing and Care

Doing all this testing can seem quite daunting – especially knowing which test meter and strips to use for which area. It’s a part of the process of keeping koi fish, and is a very necessary chore. While there is no all-in-one tester, you can buy kits that contain strips that do multiple tests. Keep in mind, though, that strips are more accurate in a tank than in a pond. We have given you some guidance on testing products in our Buyer’s Guide. It will be trial and error as you become comfortable with which means of testing is better for you and your pond set up, and use your eyes to observe any significant changes in your koi population and environment.

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Weather Conditions and External Environment

Climate will take its toll on your pond water quality. The acid in the rain and UV rays of the sun are all potential killers for your fish. Rainwater contains toxins from pollution, making it acidic. Get into the habit of testing the pond water after a heavy downfall. Watch out for ammonia and nitrite levels. Such toxins may increase under these weather conditions. Direct Sunlight can be harmful to the water and the fish in its full intensity. Sunlight increases the temperature of the water, which encourage bacterial growth such as algae. This also decreases oxygen levels. If you cannot situate your pond in a shaded area, then use natural plants to keep the water cool, such as lily pads. Of course, underwater plants do need the sunlight to grow, so it is a balancing act. Believe or not fish can get sunburnt, so make sure your koi can get shade when the sun is at its fullest. And make sure they wear sunscreen (ok, maybe not…).

Seasonal Maintenance of a Koi Pond

There will be many different tasks to do throughout the year, all necessary to help keep your pond healthy for the fish. Much of the maintenance is seasonal. One aspect which is difficult to control, especially in an outside pond, is water temperature. It is, of course, influenced by the ambient temperature. But you still need to manage it. Here we break down some of the maintenance chores into seasonal periods.

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Spring

Feeding Winter-Hungry Koi

This is the time when the water temperature will naturally begin to rise. Your sleepy koi will become more active and want to eat more. They will have wintered in the bottom of the pool where the water was at its warmest during the cold months. Once the temperature reaches around 50F on the surface, feed your koi with a good quality cold weather fish food.

They need plenty of protein to build up protective muscle. Once the water temperature increases to a regular 60F, only then can you begin to give your fish the regular food it normally has.

Spring Cleaning a Koi Pond

During the spring you’ll have to deal with the brunt of your koi pond maintenance. Here’s a basic list of what you’ll need to do.

Debris Clearance

The first job is to get the pond net out and start clearing away any surface debris that has collected.

How to Change Koi Pond Water

Spring is the best time to have a water change. Aim to replace around 50-70% of the water.

• Choose a day when there is some sunshine.
• Pump or siphon out the water into a Holding Tank(s) large and sturdy enough to hold all the fish in the pond. Gently catch the koi in your net and place them in the Holding Container so you can carry out your Spring Cleaning. This is not an easy task. Ensure there is a safety lid or netting over the Holding Tank, as they may try and jump.
• Try to complete the whole process in around 3-4 hours so as not to stress the koi in the Holding Tank. If you have a pump in the tank, then you can take longer, as this will ensure there is enough oxygen in there. You can also use a solar fountain to help move the water around if you have one on hand.
• Leave at least 1-foot of water in the pond. More is ok, but not less. You want some of the bacteria to remain.
• Remove all the plants and give them some fertilizer, as they are out of the water while you clean. Re-pot any that stay in pots.
• Clean out the bottom using a garden water hose to blast it. There are pond vacuums if your pond has become very grimy. You can also scrub the surfaces of rocks and scrub any ornaments with a small brush to get some of the algae off. Leave some on though, as you don’t want to get rid of all the bacteria.
• Take out any potted plants for re-potting, to give them a fresh start for the coming months. Take out any dead foliage as it will rot and add bad bacteria.
• Clean your bottom drain and any submerged pumps. DO NOT use tap water on filters so that some of the bacteria remains there, just use the pond water.
• Remove any dead debris such as plants, frogs and snails, from the bottom of the pond.
• As you are doing these extra jobs, the sun will dry out the empty part of the pond.
• Place everything, but the fish, back again before you re-fill.
• Re-fill with a hose from the tap water.
• IMPORTANT. Before you put the koi back, add a fish de-chlorinator. Tap water contains chlorine which is harmful to Koi. Leave to stand for around an hour.
• Turn on pond pumps and leave for another 30 minutes.

Time to put the koi back.

Reintroducing the Koi to the Pond

• With the koi still in the Holding Tank, methodically empty a bucket of water from the Tank and replace it with a bucket of the new water from the pond. The idea is to acclimatize the koi to the new water, gradually. Repeat this process a few times, observing the koi to make sure they are not Shocked by the change in temperature.
• To lessen any risk of Shock, put each Koi in a plastic bag of Tank water, and float it on the top of the pond. Allow the bag to stay open as it floats, so the fish can swim out when it is ready. This might be time-consuming, but aren’t your koi worth it?
• Alternatively, if you are sure they are fully acclimatized and ready for the pond water, transfer each one with a net.

Water changes are always a risk with koi. Done carefully and correctly then all should be well. Enjoy your koi pond for the rest of the spring.

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Summer

This is all relatively straight forward, but still necessary and important in the growth and health of your koi.

Summer Care of a Koi Pond

• Clean out the filters as often as needed.
• Get into the habit of feeding the fish from the same place every time. Do it away from any pumps or skimmers so the food is not pulled in immediately.
• Feed them for around 5 minutes and then stop so there is not too much waste.
• These are the hottest months so you need to make sure the water temperature does not rise too high for the sake of the fish and the plants. To achieve this use plenty of aeration such as pumps and air stones. Run the electrical system all day and night when it’s hot for long periods. If your fish don’t come up to the surface very often, they could be trying to cool down on the bottom. This is the coolest part in the summer. If this is happening, you need to act quickly and cool the water down. You could put in some fresh cold water using a hose. Remember to measure the water levels for chlorine etc. once you’ve added tap water.
• Also, remember that the warmer the water then the less oxygen it has. This will be detrimental to your fish so measure the water levels and keep them healthy.
• Use plants such as water lilies, water lettuce, and hyacinth, so the fish can use them as shade.
• Remove debris and any dead plants.

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Autumn and Winter

Autumn may try your patience, as this is the time of debris and decay. Let’s have a look at the main concerns.

Managing Plant Life

• Once the water temperature regularly reads under 60F, plants will become dormant. When their leaves begin to brown, trim the plants down to about 2-3inches from its base. Cut away any dying foliage and remove it from the pond. Remove any bi-annuals. Put your aquatic pot plants at the bottom of the pond for the winter. It is warmer there and might stop the roots from freezing. Alternatively, bring them indoors and put them in an aquarium for the cold months.
• Removing falling debris is vital, as decaying detritus in the pond will rot and upset the ecosystem. Your koi still have to live out the winter in the pond, so make sure you keep removing the falling leaves. One way to help with this is to use a large net over the pond. Again, be careful not to let it sink into the water as the fish may become entangled.

How to Keep Koi Pond Fish Alive in Winter

• As the temperatures begin to drop, feed your koi with easily digestible food, such as wheat germ. When the water temperature drops below 50F, stop feeding them altogether. Even if you have a sunny day, don’t feed them. Undigested food will rot in their guts. This will be harmful to them as they hibernate throughout the winter months.
• The warmest water will now be at the bottom of the pond, so this is where the fish will spend the winter. Place some air stones in the pond as you start to shut down the pumps. When the temperature of the water is below 40F, there is no need to use the pumps any longer. This is a good time to remove all pumps and clean out the filters. If you live in a climate below 50F, don’t put the filters back in the pond until the temperatures begin to rise again, or they may freeze up. If it does not get too cold, then you can put the pumps back in and set them running on low to keep up some slow water movement.

De-Icing the Pond

• If you suffer from extremely cold winters, then you will need to watch out for ice forming on top of the pond. This is dangerous and will decrease oxygen levels. You could use a Floating De-icer, (See Buyers Guide) to stop this happening. If you don’t have one of these, then you need to melt the ice with hot water, and NOT break it up. If you break it, the sound may stress the fish who are hibernating. Melt a few holes in the ice to release the collection of natural harmful gasses from the water, and allow oxygen in.

Our final word of warning is for Storm Flooding

For some, winter flooding is inevitable. If you live in such climates where this is likely, you might be better to design your pond with an overflow pipe. This will divert any excess water elsewhere when it reaches a certain point. Here are a few tips to help before the storm arrives:

• Set a fine mesh net over the pond to keep flying debris out, and stressed fish in. Make sure it is as taut as you can make it so the koi don’t become entangled.
• Empty out some of the pond water, if you know you will flood.
• All electrics should be fit with Ground Fault Circuit Interrupter devices (GFCI). This will ensure that the supply will cut out if there is an emergency.
• Stop feeding koi a few days prior to the storm, if you know it’s on its way. During the storm, the fish will become stressed and dive to the bottom of the pond. Better they do this on an empty stomach.
• Make sure all filters are empty and clean, they are going to be busy with debris after the storm.
• Some keepers recommend adding baking soda into the pond before a storm. Add around 1 cup per 1000-gallons of pond water. This helps with pH levels in the pond water. Rainwater is acidic and pH levels will drop, so baking soda helps balances it out again.
• Rainwater also depletes oxygen levels in the pond, so it helps to keep the pond aerated during the storm, if you can.
• Turn off the pumps that lead to the bottom drain so you don’t risk it pumping all the pond water out if there is a fault.
• If the koi behave ultra-stressed after the storm, add 1-lb of rock salt per 100-gallons of pond water. It will help de-stress them, but this is a one-off treatment.
• If the storm is a hurricane category, move the fish into a holding tank if you can. If you don’t have a holding tank then use the family bath or a child’s blow-up pool, (with a taut net on top). Remember you will need to acclimatize the koi before you move them.
• After the storm, you must recheck all the water chemical level readings. Rainwater does unbalance everything.
• Set the bottom drain pump back to work, as soon as the storm passes.

It may be some time before the koi come back to the surface. Meanwhile, get the water back to top quality as soon as you can.

Koi Pond Care: Buyers Guide

In this section, we’ve put together a list of most of the products we’ve referenced in this guide, with some notes and comments on each.

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Conclusion: Back Yard Koi Pond Maintenance

Keeping a koi pond is a pleasurable hobby and one where you are always learning. With our two articles on this topic (this one, and How To Build a Koi Pond Cheap), you should now have enough knowledge to set up and maintain a decent pond. A pond where you can keep happy and content koi and other fish. It is not all about cleaning and measuring. There will be many, many months for you to sit back and enjoy your water feature to its fullest. To be successful though, you do need to learn all you can. Your koi rely on you to care for them. Despite the work that’s involved, it will certainly be a pleasurable responsibility to have.

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