​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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​This fast-growing plant, which can grow rooted or floating, is named for its ability to provide baby guppies with plenty of hiding places when born. It’s also great at removing toxins from water. As is the case with most fast-growing plants, it is exceptional at taking up nutrients in the form of heavy metals, toxins, ammonia, nitrite, and nitrates from water. It consumes almost every free nutrient in the water leaving little behind for algae growth. As great as that sounds, don’t run out and plant your water garden up with Guppy Grass until you understand its growth habits.
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In our experience, it grows faster than algae, which can cause some inconvenient problems if not constantly removed from your stream.  It spreads throughout small ponds like a wildfire and once it is completely rooted throughout your stream, it has the ability to displace most of the water in your shallow babbling brook in just a couple of weeks, which means if you don’t “mow” it to the stones every week, you are in for some displacement leaks.
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Guppy grass is native to the Americas, from Canada to southern Mexico. It is an extremely popular plant in the aquarium hobby. So, basically, it’s everywhere. It’s commonly found in golf course ponds and backyard ponds that do not have circulation systems, largely due to its amazing ability to sponge impurities from the water. It only takes an inch of plant to start a new plant. So, a one-inch piece of plant can hitchhike its way to your pond on a bird that visited a golf course pond just before it stopped off at your pond.  We have seen this several times now.
If you have a golf course pond nearby (as so many of us do here in the Valley of the Sun), keep a watchful eye on your pond for any new and unknown plants showing up. The most likely place for you to see the Guppy Grass first is in your stream bed.  If you should see it, carefully remove ALL of it immediately.  It doesn’t take long for it to get a foothold and once established, it is virtually impossible to remove without a complete cleanout, and dry-out, of your organic water garden.  In short, it is rarely worth the effort.
That’s not to say that there is never a time Guppy Grass is a good idea. However, if you have a longish gravel stream bed, Guppy Grass presents a higher maintenance issue than filamentous algae.

Please check with your Pond Gnome Pond Pro to see if Guppy Grass is right for your pond!
Pros

• Provides great habitat for guppies and invertebrates to hide from predators.
• Removes toxins and nutrients from the water in large quantities

Cons

• Grows like wildfire!
• Impossible to remove from an established eco system pond once established

The Pond Gnome does not recommend introducing Guppy Grass to your Pond Gnome water garden.

​Turtles are great! The Pond Gnome has lots of clients who adore their turtle pets. And just like any pet, turtles need certain conditions to keep them happy, healthy, and safe. We don’t profess to be herpetologists by any stretch, but we can help with some basics for our area of the country, as well as some references for more information.

​Turtles are well-adapted to our desert climate, and most species will live about 30 years given a proper habitat and diet.  The most common turtle species we see in backyard ponds are the Red-Eared Slider.  They are native to the southeastern United States and northeastern Mexico. 
The second most commonly seen backyard turtle is the Mississippi Map Turtle, which is native to the Mississippi watershed, as the name suggests.  These two species likely make up 80% of the pet turtles in Arizona.
Our native species is the Arizona Mud Turtle. There are three species of mud turtles that are found in and near creeks, rivers, lakes, stock tanks, and ciénegas in central and southeastern Arizona. Mud Turtles can be relatively common in their preferred habitats. A hunting license is required to lawfully collect and possess Mud Turtles in Arizona.

​The most important thing to remember about keeping exotic pets like turtles, is to keep them properly contained.  Escaped exotic turtles do a lot of damage to our native species. Allowing them to escape into natural rivers and streams is an environmental disaster of sorts.
Proper fencing designed to contain them from both climbing out, and digging out, is crucial.  Also keep in mind they are not the top of the food chain.  If you live in an area with racoons, you must also keep the racoons out of your turtle habitat, or build you turtle pond large enough for your turtle pets to escape predation.
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​Turtles are omnivores.  They eat whatever they can catch or find, including insects, small fish, frogs, and many aquatic plants, as well as dead fish or frogs.  This makes an organic water garden a utopian environment for them!  Just make sure it is large and diverse enough to handle their foraging activities, and the biological filters are designed to handle the ammonia production of your turtle pets.
Of course, lots of folks like to hand-feed their turtles various veggies. We know of a few really spoilt turtles whose owners interact with them every single day with treats and attention, and swear that they come when called.
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​Turtles will spend most of their life in the water.  When active, they can hold their breath under water for up to 30 minutes!  During the colder months, they can enter a state of torpor and remain under water for months at a time!  Still, they should have a sunny rock to bask on in the middle of their pond where they can feel safe while soaking up the warm sunshine.  They should also have a space of terrestrial dirt, and maybe event composted mulch and a shrub or two, to hang out under once in a while.
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​Turtles need a body of water to hang out in to stay hydrated.  They cannot survive long without a healthy, organic, body of water.  Having a filtered pond big enough to swim in, to hide in, and within which to forage is optimal.  If you relegate them to an enclosure with a small water tub, know that the water in the tub will need to be changed frequently as turtles defecate mostly in the water. Thus, a properly built filtration system designed to handle their output is essential if you want to also enjoy that pond aesthetically.
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​As with any pet, you should design and build a good habitat for the creature before bringing it home. Many folks get a turtle on a whim, or by gift, and don’t have a good environment in place, causing suffering, and sometimes even death. All the good intentions in the world fall short of proper planning.
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Arizona Game and Fish Department:  http://www.gf.state.az.us/
Arizona Herpetological Association:  http://www.azreptiles.com
Online field guide to reptiles and amphibians of Arizona:  http://www.reptilesofaz.com/
Reptiles of Arizona: http://reptilesofaz.org/turtles.htm​

​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.”