Why might someone end up with a crowded koi pond in the first place?
For starters, we send newcomers who show the faintest interest in our ponds to a koi show in the area. They attend, just to see what it is that makes koi or fancy goldfish so special to us, and before they get out of there, they have spent their week’s pay on fish, fish food, plants and liner. Best of all, their head is spinning with knowledge from each of the vendors at the show!
Great! We’ll have our next club meeting at their house and help them build it. Once hooked, we make it a point to meet regularly, talk about koi, listen to the experts, learn everything we can about koi care. We learn the language and compare our current fish to those at the shows. Ours don’t really compare, so we keep adding better and better fish.
This is the common formula. Basically, we keep adding to the pond. Soon, we will need a bigger pond with all the bells and whistles, greater depth and high-class filtration. Oh boy!
Koi as Pets
My fish never fail to rush to the side of the pond when I open the door. They are all gathered at the side of the pond when I come to the pond, sort of climbing on top of each other. They are so happy to see me. They actually know me from a stranger. When my friends come over, they don’t even bother to come to the surface. It’s a special feeling to be greeted by your fish, knowing that they don’t do this for everyone.
And, we can train them! They eat out of our hands, and we can pet them. I could never do this with my aquarium fish — they just wouldn’t have it. In contrast, koi are social animals, so having just one would be to condemn it to a slow death. It has to have company, and there are so many to choose from.
I was first drawn to the shiny fish (Gin Rin), butterfly koi and the fantastic Kikokuryu varieties. I wasn’t having just any koi carp with barbels. When I saw the dark-colored Goshiki with bright-red colors, I knew I wanted one of those! In one of the lectures, I heard that the colors were secondary to the body shape. Well, now I had to have one of everything! Kohaku, Sanke, Chagoi, Bekko, Shushui, Showa, Tancho, Matsuba, Hariwake, Ogon, three kinds of Utsuri, Budo Goromo — just to name a few!
Growing a Pond
Of course, the pond had to be deeper to accommodate development of the female koi body. When they reach the magical age of three, they are sexually mature, no matter what size they are. For koi, when the water reaches 70 – 72 degrees Fahrenheit, they churn the water, create a smelly froth and stop eating for up to a week while the males push the females against the sides of the pond. For goldfish, it is not quite as dramatic, except they do it every other week for the entire summer season. That can be a huge number of babies!
So how do you tell who’s who? To keep it simple, I figured that the chasers were the males. I figured that I needed a second pond — one for males and one for the battered females. Actually, make that three ponds — one for the babies, too.
Did you know that koi and goldfish can interbreed? The results are not attractive, but for many people, if it was born in their pond, it’s beautiful and it isn’t going anywhere.
The Size Factor
When shopping, we tend to underestimate a fish’s size at maturity. When buying a cute little 3-to-5-inch koi, who really pictures the huge 30-to-36-inch monster fish it will become? Some goldfish can grow almost as large if given time and room.
Who actually factors in the size? Most people don’t even care, and truthfully, it is actually the DNA in the fish that will determine the size of each koi. Some will grow quickly and reach great sizes, while others get the benefits of high-protein foods but never grow over 12 to 15 inches.
As an example, we have a 1,000-gallon pond and added a dozen baby koi. They quickly disappeared into the mass of water, which was so disappointing. So, we went back and bought another dozen or so larger fish. Since the dozen baby koi disappeared in the pond, we could easily add a dozen 6-to-12-inch koi this time, right? However, after adding them, the pond still seems empty. The cycle repeats and repeats.
And once a koi has made its home in your pond, it’s nearly impossible to part with it. Oh, but that’s my favorite fish! I’ve had it for years! That’s my daughter’s favorite! I can’t get rid of that one! This one was born in the pond, I can’t get rid of it now… My wife would kill me if I gave her favorite koi away! The babies are so cute! Maybe I have a Grand Champion in here … in short, we tend to treat them like our own children.
Busting the Budget
The more fish you have, the more fish food you’ll need to buy. Do you remember when you had a small pond with just a few fish, you bought a small container of fish food and fed only a few pellets daily? Life was simpler back then.
Then you went to a koi show and learned that your pond was too small. You bought a large bag or two of baby koi because they were inexpensive. Another dealer at the show had a special on food! You already had plans in your head for a larger, new pond to hold all your fancy koi that would one day take Grand Champion … Then you met the best builders in the business, and they gave you a special price on your dream pond. You couldn’t wait to get home and put things into action!
We have all been there and done that. We do not look back or regret it. Now, we have our high-end koi food delivered to our homes 40 to 100 lbs. at a time. There are those, however, who cannot afford high-end foods and will shop at big box stores. (Oh, no! Their poor koi.) Truth be known, a million gallons would soon be overcrowded by koi if the owner did not learn to limit buying, to cull, or to find some other way to curb their habits. There is always a more beautiful fish to buy, and there are more fantastic hybrid colors when it comes to new koi. Maybe there will someday be Koi Anonymous group.
Impact on Water Quality
Your wallet isn’t the only thing that will take a hit from an overcrowded pond. Indeed, some of us adopt a “the-sky’s-the-limit” budget for our fish, only to cut expenses when it comes to the filters. You will likely sacrifice water quality, resulting in the need for more frequent water changes and larger filters. As the saying goes, “Take care of the water, and it will take care of the fish.” Before you start tossing medications into the pond, find out what is wrong with the water.
The issue of poor water quality actually comes from overstocking, overfeeding, and failure to do regular partial water changes and other regular cleaning. A filter needs to be cleaned or backwashed. A pond lined with rocks or stones helps by providing more area for beneficial or heterotrophic bacteria to colonize, but it also traps and holds larger organic waste.
Snails are not the answer. Anything that eats also poops, so they are not effective pond cleaners. Bogs can be helpful if you plant the best plants. If you are feeding too much, high phosphates will show up on water tests. So, you will do best if the bog contains red-leaved plants to remove phosphates, and so on. The bog should not contain more organics or soil. All in all, you will have better water quality with less fish and good pond maintenance.
KH, or carbonate alkalinity, is an integral part of keeping a healthy and stable pond. It stabilizes the pH and is vitally important to the nitrifying bacteria (Nitrosomonas and Nitrobacter). When the KH level is low, you will see nitrites building. If you don’t notice nitrites, you will notice toxic ammonia as the nitrogen cycle slows and then stops. The more fish present (giving off ammonia) and the more you feed (increasing the ammonia), the faster KH is being used up in the pond.
Fish Stressors
Fish don’t die from parasites. They die from stress. Stress leaves them weakened and open to health problems, parasites and other ailments. Overcrowding is stressful. Poor water quality is stressful. Think of dense air pollution in a city.
You may notice torn fins, lost scales or scales hanging loose on the fish. You may have frequent flashing or fish hanging beneath the waterfall. Other fish may stop eating and stay by themselves. These are common signs of lesser fish health.
Did you know that female koi need to swim vertically to develop their muscles? Thus, the depth of the pond is important. For male koi, the length and width of the pond are more important. Think about how stressful it must be swimming into each other!
If your fish are bumping into each other, especially at feeding time, there is no doubt they are sharing parasites from one body to the next. There is no such thing as an antibiotic pond or fish. All fish and ponds contain a number of parasites. However, healthy fish will not be troubled by them until they become stressed.
Natural fish stressors include loud noises, e.g., if there is construction going on nearby. Storms and seasonal weather changes can also be particularly stressful.
Ill-Advised Solutions
Why wouldn’t you just build a bigger pond? Unfortunately, the time spent in a holding pond waiting for their new pond, and then the transfer into a new, uncycled pond can be very stressful for your fish. It is not the answer to overcrowding problems. You have males and females there. What do you suppose they will do in the bigger pond when the water temperature in the spring hits 70 degrees Fahrenheit? That’s right, you’ll end up with even more fish!
Backyard breeding (in hopes of striking it rich) can be tempting, but again, the problem is the expense of keeping and feeding compared with simple selling. The Japanese koi breeders cull from their babies, starting very early and many times before their tried-and-true bloodlines are ready to show or sell. It is not as glorious as it sounds.
And frankly, if you were able to cull in the first place, I doubt you would have gotten to this point at all.
About the Author
Carolyn Weise is the customer relations manager for Ecological Laboratories, Inc. She studied ornamental horticulture at the State University of New York at Farmingdale. Carolyn serves as a liaison to koi clubs and recently joined the master gardener’s program in Lee County, Florida.
