Lucky is the pond owner who enjoys having a beautiful Kohaku koi swimming among the lily pads in their very own back yard pond. The Kohaku is the oldest and most well-known variety of koi, and is often the most popular among koi lovers.
Kohaku is a bright white koi, patterned with red. There are two types of Kohaku – one has the red pattern all over its body, which is the most common. The second type of Kohaku only has a red spot in the middle of its forehead. This is an extra-special type called Tancho Kohaku, and is a highly prized specimen because of its rarity.
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The red spot on the forehead makes the Tancho Kohaku a living, breathing model of the Japanese flag, which represents a red sun in the middle of a pure white field.
Kohaku is the most common fish to win “Grand Champion” in Japanese shows, because it is the most popular fish in Japan and therefore, the breeders of koi spend the most time producing the finest specimens of this type.

Judging good quality koi such as Kohaku is not an easy task! There are certain “pattern” basics that you can learn to apply when buying fish, but forecasting the way that pattern will look later as the koi matures is a special talent. Also, body shape and conformation are important features, and few Americans appreciate the complexities of this characteristic. Finally, the way the red, called Hi (pronounced “hee”), breaks into kiwa (the trailing edge of the Hi) or out of the white (sashi) is important. The more crisp the transition from red to white, the better.
The details concerning pattern intricacies of Kohaku during championship judging can seem tedious, so here’s a simplified method of Kohaku appreciation that, although likely inadequate in choosing show-quality koi, is effective enough to choose fish which most folks will value.

1. The white of the Kohaku should be a bright, snowy white. The brighter and the white, the better the fish is. If the white appears thin or almost grayish, the fish is not as good a quality. There should be a white band at the very base of the tail to stop the “Hi” (red) from touching the tail. There should be nothing but white in the pectoral fins and tail of the koi. Likewise, the dorsal fin should be all white.
2. The red (Hi) in the koi can sometimes be slightly orange when the fish are young, depending upon the breeder. The red can change from orange to crimson red when they mature or “finish.” In some cases, the Hi may never change if the breeding is poor. Many koi lovers won’t purchase orange-colored Kohaku for lack of faith that they will ever turn crimson. You have to trust the dealer when they assert that the “red is on its way!” Some koi are a deep, cherry tomato or crimson red from birth to death. The red should not go into the fins, and the red should not extend below the eye in the head. The red should not go below the “lateral line” on the sides of the fish, nor into the tail. Also, small flecks of red in the fish are undesirable.

When you see a Kohaku with a uniform pattern of a single, red blossom in the center of each scale, and the pattern is pleasing to the eye, it is called Kanoko (fawn). Some of these fish are thought to make a good investment, but rumor has it that Kanoko Kohaku are “going away” and the red dots won’t survive many years in the pattern, which leaves you with nothing but an expensive white fish.
The pattern of the fish can be solid (ippon), lightning strike or zig-zag (inazuma), or it may occur in spots. The appearance of two spots is called “Two-Step” Kohaku or Nidan, and three spots is referred to as “Three Step” Kohaku or Sandan. They even have names for Four Step and Five Step patterns, but they’re generally not as precious as the two and three step koi.
The body of Kohaku ought to be rather fat, rounded off, and sort of voluptuous or “Rubenesque.” The head should have fat “cheeks” in the more mature fish. The base of the tail, where the caudal fin emerges, should be fat and round instead of streamlining into the tail. The fan-shaped pectoral fins behind the head should also be big and round. The rounder and whiter, the better. Thin almond-shaped pectoral fins are a disappointment. The body of the fish should be wider than the head, which would suggest that the fish is a female, which is a good thing.
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OTHER POSTS YOU MIGHT ENJOY:
KEEPING KOI & POND FISH: 3 BASIC RULES
KOI AND POND FISH ANATOMY: WHAT YOU NEED TO KNOW
HEALTHY PONDS HAVE FILTRATION
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Your pond water should always be clean-smelling and have good clarity.  On occasion, the water might be green due to suspended algae, or slightly brown due to tannins, or even a bit cloudy after one of our famous dust stroms.
Algae is typically expected in the winter and spring when the plants are not growing aggressively. Once the plants grow, they consume more nutrients from the water, thereby starving algae of food to survive. Ponds in sunny locations experience higher algae growth, but this can be alleviated by shading the pond surface with waterlilies or floating plants like water lettuce.
Keep in mind, algae isn’t necessarily a bad thing. Your pond fish will eat algae off the rocks in your pond so it’s good to have a little of the green stuff. Too much algae can become unsightly, but can be controlled with various water treatments.
If you’re going to keep fish, it’s imperative that your pond have proper filtration. A mechanical skimmer is your first line of defense for removing unwanted debris such as leaves and twigs from the surface of the water. If left to decay in the pond, organic material can cause a host of water issues that could make your fish sick. The skimmer also houses the pump, which circulates the water and helps to aerate the pond.  A biological filter is positioned opposite the skimmer to create the beginning of a waterfall. This filter uses bacteria to break down pond waste, converting it into less harmful compounds that can act as aquatic plant fertilizers.

​Did you know your koi and pond fish have a simple heart with only two chambers? Should that even matter to you as an owner of a pond with fish? Probably not, but you should be aware of the Koi and pond fish anatomy that actually does matter to you.
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​Let’s start with the obvious. Koi and goldfish have the usual dorsal (top) fin, an assortment of bottom fins, and the caudal (tail) fin, as well as a few others.

The dorsal fin on Koi is extremely vulnerable to ulceration and it’s not uncommon for the mildest of bacterial infections to erode a hole right in the middle of it! Once the ulcer has healed, the fin can remain incomplete. So, when purchasing (or adopting) a new fish, inspect the dorsal fin to make sure it’s whole.

The two pairs of pelvic fins are the pectorals and the ventrals. These are the fins that define the landmarks for injection of sick fish because it is the safest site with good absorption.

​Next up in learning about pond fish anatomy are the scales. The scales cover the body of the fish and are of variable size, depending on the location, and they overlap at five points. People tend to think the scales overlap on the obvious four sides, but the center of the scale is underlapped by the scale behind and in front of it.

When a fish gets a deep wound, they may dislodge or shed their scales. The dead tissue and loose scales that surround a wound can provide bad bacteria with fuel to continue to infect the fish. To avoid this, gently scrub the wound with a piece of gauze soaked in grocery store hydrogen peroxide. The term for this process is debridement. It’s not meant for all wounds and should not be overdone. Over-cleaning a wound removes cells that are trying to heal, so usually only one debridement is enough.

Fish do a good job of replacing lost scales over the course of several weeks after their loss. However, the replacement scale is of a finer (thinner) quality and sometimes unevenly marked compared to the original scales.
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​The gills are to a fish what your lungs are to you: a delicate organ system that exposes all of the blood to oxygen. The gills are pushing the blood through capillaries that exchange with water, not air.

What most people don’t know is that the gills perform another important function: the excretion of fish waste in the form of ammonia (like we exhale carbon dioxide). The gills are the most important waste excretion organ in the fish’s body. Damage to the gills by way of infection from bacteria, destruction via viruses, infestation with parasites, or just damage from medications or poor water quality, can impact the fish far more than just breathing.

The operculum is the thick boney covering on either side of the head and protects the gills. You may need to lift the operculum to examine the gills, but don’t lift it too far or it might tear. The gills of any sick or dead fish can be photographed to provide important forensic information after a fish disease outbreak.
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​Koi and goldfish don’t need eyes to live. In fact, there’s a genetic mutation that causes one out of ten thousand fish to hatch without any at all! If a fish loses one or both eyes through trauma, it can still find food perfectly well with their barbels, lips, and mouths which are loaded with sensory structures like taste buds.

There’s a fat cushiony blood supply to and from the eye called the choroid plexus, designed to protect the eye from any trauma. Sometimes the choroid swells due to a blow to the eye. This is temporary and the eye may sink back into the socket over the coming week. A popped eye for an indefinite period could be the sign of another problem that may require the help of a fish professional.
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​You’ll find Koi and pond fish anatomy shows a very simple digestive tract. They have an esophagus that comes from the mouth and goes to the “stomach.” Their “stomach” is actually just a stretchy wide spot in the top of the intestine for food storage before it’s passed into the intestine.

Koi tummies hate to be full in cold water. When this occurs, the lining of the intestine is damaged and bad bacteria can get through the damaged lining into the blood stream. The fish show no obvious signs of this, but may die later in the spring when the water warms and the bacteria go to work on the poor fish. This is one reason we recommend that you not feed your fish when water temperature reaches 50 degrees Fahrenheit or below.

​The air bladder is an amazingly delicate structure. It fills with air via a thin veil of capillaries extending over its surface, and air is released by way of a thin tube that comes from the caudal sac. The air is burped into the esophagus, which then escapes through the mouth. The air bladder is balanced to the weight of the fish against the water, which is the primary means by which the fish can hang in the water without paddling the whole time.

If a fish is floating upside down on the surface, something has happened to the air bladder’s ability to let air out, so it is then too large and too buoyant for the weight of the fish. A problem with the air bladder can also cause the fish to sink to the pond bottom. This usually occurs when the spinal cord is damaged near the point where the nerves that regulate the air bladder emerge. Sometimes the air bladder can be removed or surgically corrected, enabling the fish to swim normally.
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​Fish are boney, and ornamental pond fish are no exception, as you’ll see in the pond fish anatomy diagram below. Unlike the bones of sharks and stingrays, their bones are truly bones and not cartilage. The bones of a fish are not meant for bearing weight because, in water, the fish is pretty much weightless. The two principal stresses on the fishes’ bones are hydrostatic pressure from the water, and the push and pull of the fishes’ mighty muscles on those bones.

That’s why, when you net a fish and carry it in that net, you’re putting a unique force on their skeleton which can damage them. The fish is bent into a u-shape and its full weight torques the skeletal bones. Broken backs are a common result. Instead, use your net to catch the fish and then slide a big plastic bowl under the fish to carry it.

If a fish suffers from a broken back, the cure is simply time. The fish may compensate for the injury – even if crooked from that day on – or it may simply starve to death.

​Fish muscles are different from your muscles. If you’ve ever seen a fish filet, you remember that there are red and white lines in the meat. The muscles of a fish are oriented in thick bands called somites. These bands are stacked all down the sides of the fish in thick, orderly rows.  Let’s go back to carrying fish in nets to find out why this matters. When the process causes damage to the back, it also destroys at least some of the nerves to at least one of the bands of muscle.

Whenever a somite dies, the muscle gets smaller and a kink in the fish will be seen. The concave side of the bend is the side with the dead somite. If you don’t carry fish around in nets, this is unlikely to ever have been seen in your collection.
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No, Koi can't bite you. ​In the back of the koi throat, emerging from the lower gill arch in the back, there are three to four molars. These molars have serrations on the top like your own molars. They’re broad, crowned teeth used to destroy shells and pulverize insects and crustaceans scavenged from the pond bottom. These teeth are shed and replaced continually through the life of the Koi. They are too far back for you to ever be bitten by a koi.

Hopefully you now feel a little more confident in understanding Koi and pond fish anatomy and how it relates to your care for them. Finned friends are just as important as furry friends but are often less understood since you can’t hold and cuddle them. Enjoy watching your fish and familiarize yourself with their behavior. That way, it will be easier for you to identify when something might be amiss.
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​Butterfly koi are beautiful, elegant fish; however, quite a few Koi connoisseurs think of them as mutts?  Some go so far as to say they’re not even Koi! Let’s take a look at how butterfly Koi originated so you can decide for yourself if you think these long-finned creatures are worthy of your pond.

In the early 80’s, a population of common brown & gray carp with long fins were found in a series of canals and ditches in Indonesia. A company in New York took an interest and brought the fish into the United States and sold a few. They did not sell well because most fish lovers thought they were ugly. However, an enterprising and curious group of breeders at Blue Ridge Fish Hatchery placed an order for a dozen of these fish to see what exactly they were. Ugly, with long fins, is what they discovered.
Rather than call it quits on these new-found fish, the breeders decided to breed them with their finest, regular-fin Koi and made several discoveries:

• Longfin genes are dominant, so breeding the fish back to color would not breed out the long fin gene.
• Longfin Koi are robust and disease resistant.
• The fish could be bred back to color and many colorful lines of longfin Koi have been created at Blue Ridge Fish Hatchery.

Wyatt LeFever was the original breeder at Blue Ridge Fish Hatchery who spearheaded the cultivation of longfin Koi. One day out of curiosity, his son Randy visited the tanks to see the fish. “Dad,” he exclaimed, “they look like butterflies!” And the name stuck.

​As Butterfly Koi grow, they become more impressive because the fins keep growing until the blood vessels can no longer sustain further growth. The older the fish, the longer and more impressive the finnage. So, a full-grown Butterfly Koi looks like a long, slinky dragon moving through the water. Their barbels (whiskers) even grow long and can fork into elaborate designs.
Butterfly Koi seem to lack some of the body size of regular Koi, but the overall fish can run as long as 36 to 40 inches in the right pond with plenty of food. Over the years, Butterfly Koi will become broad, healthy fish with great personalities, given proper care. They are graceful and pleasant to view in the pond.

​Since pattern means a great deal to the value of a regular Koi, stands to reason that a good, recognized pattern with bright colors would increase the value of a Butterfly Koi, too. But there are a few noticeable elements – such as fins. While a Butterfly Koi is more valuable when it has a properly defined and positioned pattern in the color, beautiful fins can often make even a poorly patterned fish look beautiful.
In addition, lemon and platinum ogons (solid color) in the Butterfly category are amazing when they reach adulthood. When you grow a metallic yellow or platinum ogon Butterfly Koi to an impressive, large size, their body movement is more graceful and slow. The fins are long, but the uniform gold or neon-white color is brilliant in the water and such fish look like fireballs or comets moving through the water with their fins streaming behind them.
​At one time, we had one of each, named Moonlight and Sunshine. Sadly, they fell victim to a hungry predator before we put protection in place.

Black Butterfly Koi are seldom found and the rarest is the doitsu, karasu Butterfly. This fish is black, has no scales, and possesses long fins. It looks truly magical in the water, especially when it comes up to the surface of the pond during feeding time.
Black Butterflies grow up and become very large because their genes are not as strained as some of the brighter colored fish. And if they have no scales, the body is a glistening jet-black color. The fins keep growing until the fish is broad, and streams like black robes behind it, reminiscent of a jet-black dragon.

So how did the fins of a Butterfly Koi get so long? It’s actually the result of an aberration causing the fin length gene to fail in turning off. The gene is a dominant mutation with recessive lethal effects. In fish, the fins are supposed to grow to a genetically specified length, then stop growing.
In the high fin mutation, the fins don’t get the “stop growth” message and they keep on growing. This happens in individual fish of many species from time to time. A few notable examples are Siamese Fighting Fish, Simpson’s Hi Fin Swordtails, Long Fin Oscars, and Long Fin Black Tetras. Any time the mutation is encountered and identified; it is bred into a species to see if it would make that species more commercially appealing.
Like any other Koi, the fins of the Butterfly Koi are made up of dozens of rays of cartilage that radiate outward and support the fin. These rays generally grow very straight, but past the point of normal length, they can grow wavy. The fish that grow straight rays even into the lengthier parts of the tail are more impressive looking and therefore more valuable.

​One problem with Butterfly Koi is that they are often handled the same way as regular Koi. Broken fins and tails are par for the course by the time the fish is an adult. So, it’s common to see bends and waves in the fins and tail of Butterfly Koi partly because of growing that way, but also due to netting damage as a juvenile.
As an adult, a split tail or fin often does not heal well and remains split. This is irrelevant to the casual observer, the impact of the fish is the same, but you might notice variations in fin quality, and you may decide to choose one fish over the other based on that observation.
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​The answer to this question depends on who you ask. Japanese breeders call Butterflies “Hirenagagoi,” while regular Koi are called “Nishikigoi.” They won’t judge Butterflies using traditional criteria because they’re too slender, the ratio of fin-to-body is disproportionate, and they don’t exhibit color patterns in the way traditional Koi do.
There are many keepers of traditional Koi who actually find Butterfly Koi to be superior to normal Koi. And today, many of Japan’s prestigious breeders breed them today. Butterfly Koi are very popular in Europe and North America and you can find them at most fish-retailing locations.
If you haven’t added this fish to your pond yet, this might be the year to do so! You’re sure to enjoy their elegance as they glide through your pond beneath the lily pads.