​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.

Koi people tend to fall into two categories: those that love keeping them as pets in their pond, and those that collect them like a prized car that’s only driven on Sundays or parked at car shows. There are actually quite a few analogies that can be made between Koi and cars. And since we’re kind of into cars, we’ll use those analogies shamelessly.
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​The sedan represents the attractive, domestic Koi of good quality. It’s a healthy fish that has been spared a long trip from overseas. The bloodlines of most domestic fish are short, and the classic ancestral stock is not long ago. So, the fish are sturdy and dependable. But with a lack of refinement comes a less refined look. Domestic, durable Koi of average to good quality make wonderful, robust pets, and are an enjoyable addition for your pond as wet pets.

​If you’re looking for something fancier, you’ll generally pay more to own it. Typically imported from Asia, these Koi are more expensive than their domestic counterparts, but in general, they’re prettier. Their good looks, plus the cost of shipping, is why they’re more expensive.

​There is a breed of Koi owner who doesn’t care about price; they simply need to have the best. There are handcrafted fish available in Japan that are finer than any other Koi you can buy anywhere else in the world. These fish are usually large and have already won a Koi show in Japan.
What’s interesting is that when the driver of the handmade Italian sports car drives down the road, people only marvel at the value of the car – not the skills of the driver.
The grand champion Koi is no different. It’s a profoundly expensive fish that is bred, raised, and shown by a Japanese craftsman, then sold to a trophy hunter in America. No skills are called upon to buy a fish that already comes with a trophy. Only a fat wallet.

​These performance vehicles are lovingly handcrafted in America. They’re fast and beautiful. The comparison in Koi is the hand-selected small import or domestic Koi that goes on to take a trophy in a local show. In this case, the owner of the fish chose it based on its assessed future quality and they raised it to sub-adult or adult status and put it in a koi show. Victory in a Koi show with a fish you chose and raised by hand is a testament to your ability to judge fish, to identify quality, and to provide the kind of husbandry needed to produce a champion from a small fish you hoped was a diamond.

​Koi breeders have been known to sell the poorest of their culled baby Koi into the fish bait market, and as feeder fish for consumption by larger fish in pet shops. The common alternative is to either bury the fish, or sell them as “pond grade” Koi.
Beginner Koi collectors sometimes think simply being orange is enough to be a decent Koi. The all-yellow Koi, called the Lemon Ogon, is wildly popular and easy to produce. It could be considered one of the finest of the economy cars because it is abundant and not unpleasant to own.
There’s nothing wrong with economy cars, or economy Koi, but exceptional colors or patterns don’t generally occur in this group. These fish are certainly pleasant to own – they just won’t win a show.

​What this means is that there are different types of Koi and, as you may have assumed, there are different types of Koi owners.
And here’s the interesting part: while the owners of economy Koi are unlikely to expect all Koi to be low cost and lower quality – the converse is not true of some of the folks who keep and show the finest Koi. There’s a big difference in the way Koi need to be kept, and the way they are kept by the Koi aficionados. Thus, when choosing a pond construction method, knowing which one you are will determine how the pond needs to be built. In fact, it’s one of the first questions we ask when someone calls us about building them a “Koi pond.”

​Though the term "water garden" is normally used to describe a particular type of natural or man-made water feature that is used for a relatively specific purpose, there are many other types, styles and designs of water feature. And it seems most people want water in their garden in some way, shape or form -- it just doesn't seem complete without it.
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​Water gardens first originated in ancient Egypt when the Egyptians channeled water from the Nile into their palace gardens. In their water gardens, they primarily grew lotuses, a primary source of medicine and a plant considered to be sacred. They also grew Papyrus and kept fish in their ponds – over 3,500 years ago!

The earliest planned gardens that included ponds were probably in Egypt, documented as early as 2,800 BC. They were also great garden designers. In most of their garden designs, the water garden or pond was the central focal point of the entire landscape! The gardens were created around the pond with blooming aquatic plants like lilies, lotus, and papyrus. Ornamental plants and trees came right up to the edge of this oasis. To top it off, they would create lots of space to lounge and enjoy the outdoor area. So, outdoor living environments are not actually a new trend.

Decorative ponds and fountains were a major feature in gardens of the Middle Eastern civilizations of Mesopotamia, as a result of the need for irrigation canals. The design tended to include four water features in the form of a cross, thought to stem from the four rivers of the Garden of Eden and the concept of "flowing to the four corners of the earth."

Water gardens, and water features in general, have been a part of public and private gardens since ancient Persian and Chinese gardens. Water features have been present and well represented in every era and in every culture that has included gardens in their landscape and outdoor environments. Up until the rise of the industrial age, when the modern water pump was introduced, water was not recirculated, but was diverted from rivers and springs into the water garden, and then exited into agricultural fields or natural watercourses. Historically, water features were used to enable plant and fish production for both food purposes, as well as for ornamental aesthetics.

It’s pretty cool how similar people and civilizations are over the millennia, and how we all want and need a connection with water. These ancient people surrounded themselves with water and beautiful plants, and pioneered concepts and things we still use today – like irrigation, garden design, arbors, edible ornamental’s, and even ornamental fish keeping.

Aquatic plants were among the earliest flowering plants. Fossil evidence places an early form of waterlily at 125-115 million years BC! One of the most important plants of the world (and an aquatic!), rice was domesticated 4,000 years BC, based on evidence in Thailand. The value of many aquatic plants as food cannot be underestimated.

The lotus appears in ancient Egyptian hieroglyphics as early as the First Dynasty (2,950-2,770 BC). Legends, myths, art, and physical evidence bespeak its importance in ancient Egyptian culture and religion. How and when lotus reached Egypt is not really known, but the Greek historian Herodotus wrote of its presence there in the fifth century BC. Lotus seeds were found as a part of the Hemudu Culture in ancient China as long ago as 5,000 BC, and presumably were native to that region. Chinese poetry from the Zhou Dynasty (1,122-256 BC) also speaks of lotus. It is indeed a mystical and sought-after plant even today!

​Fast forward to present day. Water gardens can be defined as any interior or exterior landscape or architectural element whose primary purpose is to house, display, or propagate aquatic plants. Despite the primary focus being on plants, most also house ornamental fish, calling it a fish pond. Most people, though, just refer to water gardens, ponds and fish ponds as “ponds.”

Water gardening is basically growing plants adapted to ponds. Although water gardens can be almost any size or depth, they are typically small and relatively shallow, generally around 24” in depth. This is because most aquatic plants are depth-sensitive and require a specific water depth in order to thrive. And what better place to garden when it’s 110 degrees outside than standing in water?

Ponds and water gardens are what you make of them. Luckily, The Pond Gnome just happens to create custom build-to-suit water features. Tell us your dream, and let us help make it a reality for you! Or, you can peruse our pricing and use our cool Build & Price Tool to select your options and build to your budget. It’s easy and fun!

​It’s absolutely heart-breaking to wake up in the morning and find your fish floating in the pond – especially when you don’t know why it happened. If they don’t have any visible wounds on them, and it’s mid-Summer in Phoenix, the cause is probably suffocation.

Several factors can contribute to this issue:

• The build-up of mulm on the floor, creating a toxic environment of methane being released into the pond
• Too many fish in the pond competing for the available oxygen
• An over-abundance of plant life

​If any (or all) of these factors combine with the already low oxygen levels in warm water, the pond fish can suffocate. Here in Phoenix, during the summer, our nighttime lows can remain above 90 degrees! This sets up a very oxygen poor environment in our water to start with.  Warmer water naturally holds much less oxygen than colder water.

​An over-abundance of plant life provides plenty of oxygen in the daytime, but exhales carbon dioxide at night (photosynthesis). That’s right: too many plants allowed to grow out of control actually rob your pond of oxygen at night. Now, that’s not so bad in the wintertime, when cold water is oxygen-rich and the fish’s metabolism has slowed to a dormant rate, so they’re not in need of as much. But in the summer, the fish are more active, their metabolism is at full-throttle, and they need all the oxygen they can get.

Plants grow like wildfire in Phoenix from Spring through Fall, taking up the nutrients from the fish waste and adding shade and oxygen to the water all day long. Then nighttime comes along, and the plants reverse this process, stealing oxygen from the pond and releasing carbon dioxide, just like a human inhaling and exhaling. If you have a lot of fish (measured in inches) competing for that oxygen, someone’s going to lose -- and the plants can hold their breath longer than the fish.

Sun exposure, aeration, depth, plant varieties, etc. play a role in healthy pond-keeping practices. The following preventative measures are rules of thumb, and you need to remember that each pond is an individual and unique unto itself.

The first rule of ponding is to not over-fish your pond. Yep, there are a lot of really cool fish out there, and people are tempted to collect them all. If you want to do that, build a bigger pond with appropriate filtration for that goal. Otherwise, choose wisely. 

Experts agree that you should keep your fish collecting to between ½” and 1” of fish per ten gallons of water. And if you have other aquatic life in the pond, such as a turtle, you need to take that into account, as well. 

A well-maintained ecosystem pond really should only need a complete drain & clean every 3-5 years here in Phoenix. Preventative measures can extend that timeframe, or even eliminate it. That estimation changes depending on how many fish you have, other aquatic life in the pond, and how much food and waste accumulate. 

​The toxicity of the mulm building up on the floor of a pond depends on many factors: the types and size of your fish, the circulation system on the pond, the filtration system on the pond, etc. Preventative measures like netting the floor or adding sludge digesters to the pond regularly could actually keep you from ever having to worry about this issue.

​If your pond wasn’t originally planned for abundant fish-keeping goals, you should err on the side of caution when adding fish and stick to the ½” of fish per 10 gallons of water recommendation. 

If you’re just starting to think about a pond, you need to make sure you (or the professional you’re hiring) are clear on your goals of desired fish-keeping so that the design of the filtration system is appropriate.
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This is a big part of maintaining an ecosystem pond. In the wintertime, it’s no big deal because the water is cold and both the fish and plants are fairly dormant. Plus, a bit of extra dormant plant material in the pond makes for great cover for over-wintering amphibious life.  

But once Spring hits, those plants start growing like crazy! Just trimming off the dead leaves isn’t enough. You need to make sure you’re keeping the roots under control – which also has the added bonus of preventing water displacement leaks. A good rule of thumb is to keep your plants from covering over 50% of the pond’s surface area. If you have stellar aeration, you can have more; less aeration, less coverage. Sun exposure and depth play a role, as well.

Ponds need regular maintenance. Most well-built ecosystem ponds with appropriate filtration for their size need as little as 10 minutes a week, and provide hours of enjoyment. But it has to be done.

If you are unable, unwilling, or just plain too busy to do the maintenance, but still want a gorgeous living water feature, The Pond Gnome has maintenance programs for folks who want to do a little, a little more, or not a bloody thing!

​How can we help?