Strohl's Herptiles

02/16/2025

Well...

Couldn't get to the IRBE show in Clarksville today. I did my best, but the weather beat me in the end.

At least the axolotls got to go for a ride before the flooding, snow and ice beat us back.

Terribly sorry if you were looking for us at the show.
We'll be back in March.

Send a message to learn more

02/15/2025

Prepping some new stuff for the Indian Reptile Breeders Expo tomorrow!

Just finished a few Fluorescent Mushrooms and produced more "desert stone" shelves, feeders, high hides, and other decor for the terrarium :).

Will also have new mushroom feeders, basking shelves, etc, as well as "limestone fossil" shelves and decor.

Oh! almost forgot: Fresh emu eggs from our blonde emus.
Some people already have chicks this season - and they make excellent (giant) omelets, too :)

02/07/2025

I love this picture! It shows the three type of chromatophores (pigment cells) in and around the eye of a hatchling leucistic axolotl. In babies, these cells are much larger than they are in adults, making them easier to identify under low magnification.

You can clearly see the sparkling iridophores with their stacks of guanine crystals, the dark melanophores loaded with eumelanin, and the yellow xanthophores full of yellow pteridines.

Normally, the melanophores have branches, called dendrites, that extend out into the surrounding tissue, but the development of dendrites is suppressed in leucistic axolotls.

02/02/2025

We found the copper gene!

The formal paper was published in Scientific Reports in December of 2024. I’ll add a link to the published paper at the end of this post.

The copper mutation (cu) is a simple recessive gene. Axolotls that inherit two copies of the cu gene have a distinctive reddish, coppery tint to the skin with chocolate-brown spots (pic below alongside a typical wild-type), and dark brown or pumpkin-color eyes. Like human gingers, copper axolotls produce melanin, but it is mostly the red-orange pheomelanin rather than the dark brown to black eumelanin produced by wild-types.

In fact, when I brought the first batch of copper/wild-type hatchlings to the lab for RNA sequencing, I was all-in on a bet that the gene mutation responsible for the copper phenotype was the same one that most often causes red hair in humans, a deletion of the melanocortin-1 receptor (MC1R) gene found on our chromosome #16. I was wrong - but close!

Note: There are actually several slightly different mutations that commonly produce red hair in people, the most common being V60L, D84E, R142H, R151C, I155T, R160W, V92M, R163Q, and D294H. Although they are all mutations of the MC1R gene, and all result in red hair in homozygous people, the specific changes are at different points in the gene, resulting in slight differences in the way the gene is expressed. They also have other effects, like greater pain resistance, greater sensitivity to opioid medications, and an increased tendency to develop melanoma. The MC1R mutations originated around 30,000 years ago in Eurasia and have become common in some parts of Europe - particularly Scotland and Ireland.

There is another gene mutation that produces red hair in many people. It is a deletion of the gene for Tyrosinase related protein type 1 (Trp1). The Tyrp1 mutation is the most common cause of red hair in people of native African descent.

It is a mutation of this gene, Tyrp1, found on chromosome 6 of the axolotl, that produces the copper phenotype in axolotls!
We determined which gene mutation was causing the copper phenotype by comparing the RNA produced by copper hatchlings with the RNA produced by their wild-type siblings. Sometimes this is a very difficult process, since there are literally tens of thousands of different mRNA molecules produced in any organism, so it’s best to have a pretty good idea of which one to check for. Finding the axanthic gene, for example, has been a real pain. In this case, though, we got it right on the second guess.

Once the Tyrp1 gene was identified as the likely culprit, CRISPR-Cas9 was used to knock out (break) the Tyrp1 gene in otherwise normal, wild-type embryos. The resulting “crispant” babies were coppers, confirming that the Tyrp1 mutation was the cause of the copper phenotype.

I know it might seem unimportant - maybe even wasteful of time and resources - to make discoveries like this. I'm not going to pretend that I had any profound reasons for doing it other than curiosity. Knowing the identity of the copper gene in axolotls won’t save any lives or solve great problems, right? But wait…

Consider what I just said: The copper axolotl has a mutation of the SAME GENE that causes red hair in many humans. Humans and axolotls have many of the same genes - most of them, in fact - as do all other vertebrate animals! Understanding what each gene does in one organism is a pretty good indication of what it does in all of the others. It is much easier to study genes using axolotls than using humans (or about anything else, really).

Also remember that each gene in an organism affects many features and functions of the organism, and we are only beginning to develop the tools needed to discover exactly how genes function and interact to build and operate a living thing. Just one example: The MC1R gene influences formation not only of the melanocytes that color skin, hair, and eyes, but also the formation of structures within the sensory neurons that detect temperature, pressure, and pain. As a result, when preparing for surgical procedures an anesthesiologist has to be aware of and account for the fact that the patient is a redhead because gingers have a higher sensitivity to some forms of pain, though they have a higher tolerance. This means they require a higher dose of some anesthetics.

The Tyrp1 gene in humans results in rufous OCA (OculoCutaneous Albinism), a form of albinism that affects people with dark skin from southern Africa. People with rufous OCA have reddish-brown skin, ginger or red hair, and hazel or pumpkin-brown eyes. It also increases the probability of basal cell carcinomas, melanomas, and cataracts.

BTW: Mutation of the Tyrp1 gene in dogs produces “chocolate” labradors. Tyrp1 mutations also produce ginger cats, Duroc pigs, brown bears (including brown “black” bears), as well as red minks, llamas, etc.

Combination of the copper gene with other color-influencing genes each produces different phenotypic effects. Melanoid coppers are a uniform chocolate brown all over. Axanthic coppers have the distinctive brown spots on a background of pale cream or milk-chocolate brown. Leucistic Coppers have unusually pale eyes with brown or pumpkin-color irises. The reduced melanin in the choroid layer of the eye often results in the “red pupil” often visible in pics of all of the various copper variants. Take a look at the pics below.

If you're interested in the deep-dive details, here is the paper identifying the Tyrp1 mutation as the source of the copper phenotype:

https://www.nature.com/articles/s41598-024-73283-1

01/26/2025

I see a lot of posts and messages asking for help identifying the s*x of an axolotl. Often those also describe the typical horror-show in which someone had two "females" that suddenly started churning out eggs. That SHOULD be a rare event - but it isn't.

Identifying the s*x of an axolotl is easy… sort of.

The catch is that there is no absolute way (short of genetic testing - which I'll discuss in a bit) to determine s*x before they reach s*xual maturity, which is typically between seven and 11 months of age - but can be significantly longer!

In most cases a breeder can reliably determine s*x by 8 months of age, and often much earlier, if they know what to look for and have genetically fit, uniform clutches to work with.

Before going on, I do want to address something that came up in discussions a couple of years ago. Some people suggested that it is possible to identify s*x in very young juveniles - even hatchlings - by looking at their internal organs through their skin. NO.

To be clear: Yes, you can see right into the guts of juveniles under about three months old - especially in albinos, leucistics, and most hypomelanistics. Unfortunately, visual identification of the s*x of a s*xually immature juvenile without actually dissecting them to examine the s*x organs is nearly impossible.

This is because gonadogenesis (formation of te**es and ovaries) doesn’t take place until 30-70 days after hatching. The s*xes are completely indistinguishable prior to that event, both externally and internally. Even after the go**ds begin to differentiate, dissection and direct examination of the gonadal tissue is necessary for proper identification. There is little physical difference between the ovarian and testicular tissues and their associated structures until much later in development, at s*xual maturity, when egg formation expands the ovarian ducts, by which time the skin is no longer thin enough or transparent enough to see those structures. While the internal organs are somewhat visible, almost all that you can see in the belly is the intestine.

Contrary to what a lot of online sources suggest, s*xual maturity for most axolotls comes around seven to nine months of age. The exact timing of s*xual maturity depends on overall health, availability of protein in the diet, and genetics. In general, the healthier and better-fed axolotls reach s*xual maturity earlier than those that are ill and/or poorly fed.

Just as some clutches show HUGE variation in growth rate, those same clutches often have HUGE variation in timing of s*xual maturity, which can present serious problems when trying to s*x juveniles. Almost all of that variation, though, can be eliminated within three generations by careful selective breeding.

Once a genetically uniform, healthy clutch reaches s*xual maturity it becomes pretty easy to distinguish males from females. As a general rule, in a genetically uniform, healthy clutch with uniform growth rates, all of the males will become s*xually mature at about the same time - within 2-3 weeks of one another, at most. This is typically around 7-8 months of age. Females mature much later, but that doesn’t present a problem for s*x determination: If all of the males in a clutch have clearly “popped” within a short time, all of the remaining animals that have not “popped” are female! Of course, I would wait a couple of weeks to be sure.

“Wait” some breeders will object. “I have seen males that popped long after the other males in their clutch.” Yep. In general, males that are extremely late bloomers are almost always infertile (I say almost always because I assume there are exceptions, though I have never seen such an exception myself).

Axolotls have only one body opening that serves for all waste excretion and s*xual functions, called the cloaca, which is the opening just behind the legs at the base of the tail. They have nothing equivalent to a p***s, and have no external ge****ls.

In females, the cloaca has a small bump toward the front, and is raised a bit on the sides where small muscles are used to pick up and hold onto a s***m cone when mating. The female cloaca doesn’t change much at maturity, and looks about the same as that of any immature juvenile to the untrained eye.

In the pic of the axanthic female you can clearly see the small bump on the cloaca of a female axolotl above the red arrow. This is an 8-month female axanthic.

In males, though, there are big lumps on both sides of the cloaca, called seasonal papillae (which just means “bumps”). They are always there in s*xually mature males, but they are much larger and more obvious when mating season rolls around - though for axolotls raised in artificial environments this can be any time of the year, or always!

These big lumps contain specialized glands that secrete pheromones (chemicals that act like perfume to attract and pique the interest of females), as well as secretions that increase the motility and survival time of s***m.

In the pic of the GFP copper leucy male you can clearly see the enlarged glandular tissue on the cloaca. This is an 8-month male GFP copper leucistic.

As axolotls mature, you may notice some other s*xual differences.

For example, males tend to have longer tails than females of the same genetic background. Males also tend to be leaner, especially toward the back of the belly. The difference isn’t great enough or consistent enough to be a reliable indication of s*x, though, and certainly can’t be used when comparing axolotls of different genetic backgrounds.

Females tend to be plumper and rounder, especially in the belly. This is mostly due to the fact that females store eggs for a long time in preparation for mating. It is also because males tend to be a bit more focused on finding mates at certain times of the year, and may focus less on eating during those times.

Are there other ways to determine s*x? Sure!

S*x determination in axolotls is not what we mammals are used to. Mammals, including humans, have a special chromosome, the “Y” chromosome, that most of the genes needed to turn a developing human into a biological male. The most important of these genes are the SRY(S*x-determining Region Y) gene, which tells the developing go**ds to become te**es, and the DAZ genes, which are required to produce s***m.

This means that anyone with a Y chromosome is biologically male… er… usually.

Note: There are interesting exceptions to this rule. There are a lot of genes that work together with the SRY and DAZ genes to build a male body. Testosterone, for example, is needed to signal the te**es to mature and “drop” into the external sc***um sac. Testosterone also signals muscle, bone, and other tissues to form a masculine body type. That only works if other genes that instruct the cells to make the testosterone receptor protein are working correctly. If those genes are missing or damaged, the cells cannot receive the signal to form masculine tissue structures. A mammal with any of several such mutations will be genetically male, but physically female. There are human families in which this is actually common. It is also possible, though very rare, for humans to be mosaics of both male and female tissue! With 8+ billion people on the planet just about every rare thing happens to someone.

The Y chromosome is very small compared to other chromosomes in humans and other mammals. Through a process of elimination, the Y has retained the genes needed to produce males, and little else. This makes it easy to identify a male mammal just by looking at its chromosomes under a microscope. A male human, for example, will have 22 pairs of matching chromosomes, and one pair, the X and Y, that don’t match.

To see examples of the difference between the chromosomes of males and females, Google "karyotype" images.

ALL of a human female’s chromosomes are in matching pairs, since she will have two X chromosomes.

Because males have two different s*x chromosomes, the X and Y, we say that male mammals are heterogametic, a word that roughly means “different s***m”. This means that it is the male mammals that determine the s*x of the babies. Babies that get a Y chromosome from the male are males, and those that get X chromosomes are female.

Axolotls don’t work this way.

Similar to birds, axolotls have what is called a ZW s*x determination. In axolotls (and many other amphibians, birds, some fish, and some reptiles), the female has a W chromosome that has the genes needed to make an embryo female. Without the genes on the W chromosome, an embryo always becomes male. Females have the Z and W, and males have two Z chromosomes. That makes the female axolotl the heterogametic s*x.

In birds and most other organisms with ZW s*x determination it is pretty easy to identify the s*x just by looking at the chromosomes from a single cell. Just as the Y chromosome is unusually small in mammals, the W is unusually small in birds. This means that you can take a picture of the chromosomes in a single cell (a karyotype) and see that there is an unmatched pair.

That won’t work with axolotls, though. The s*x-determining genes of the W chromosome are packed closely together, but there are a lot of other genes on the W along with them that are also present on the Z chromosomes. This makes the Z and W the same size and appearance under a microscope.

Most species of animals have very distinctive, easily recognizable s*x chromosomes. The chromosome that has the s*x-determining genes is usually very small compared to its partner. Some species of animals have indistinguishable s*x chromosomes because their s*x-determining system is relatively new, in evolutionary terms. To be clear: “relatively new” means within the last few million years.

This may well be true of axolotls and their close relatives, but I doubt it. I suspect that the s*x-determination system of salamanders is really very old, but that the mechanisms that cause s*x chromosomes to differentiate in other animals are messed up due to their absolutely huge, bloated genomes, which are absolutely choc-full of “transposons” that don’t really do anything but copy themselves.

But there is a “sciency” way to identify the s*x of axolotls - even before they hatch!

In 2017, Melissa Keinath, working in Jeramiah Smith’s lab at the University of Kentucky, developed a simple PCR test to determine the s*x of an axolotl from a tiny sample of the animal's cells. The test has been refined so that it can be done with a skin swab or a little bit clipped from the tip of the tail (which, of course, grows back with no ill effects).

There are several DNA base sequences that have been identified in the axolotl genome that are found only in females. Keinath’s test amplifies one of those, a 219 base pair DNA fragment, which can then be easily identified using gel electrophoresis. The whole process takes a couple of hours. This sequence isn’t really part of the genes that make an axolotl female, but since it is only found in females, it works to distinguish male from female. Using one of these s*x-specific sequences (published in 2017), anyone with PCR reagents, a PCR machine, and a gel electrophoresis box can s*x axolotls of any age.

Please note that university labs won't do this for you. It is just a bit too expensive, time-consuming, and low-priority for people working on doctoral projects and clinical research. But there are a couple of people in the axolotl community who offer genetic s*xing, or use it to guarantee the s*x of their young juveniles. Lizzy's Lotyls is doing this now.

Coming soon…
Just last Summer, researchers at the Ambystoma Genetic Stock Center at the University of Kentucky identified the specific gene (or genes, depending on how you define “gene”) on chromosome 9 that actually makes an embryo a female, and they will be publishing the results soon.

Even cooler: It is now possible to link a fluorescent protein gene, like GFP, to the s*x-determining region in such a way that a s*x-linked trait is produced! Using this method, axolotl lines would then be bred with this trait so that females have it and males don’t, making s*x identification at any age easy and flawless - as long as you’re not producing GFP clutches.

01/24/2025

Here we go again.

Another scammer is trying to sell Lokai the split mosaic (see link below). That first pic in the post is definitely Lokai in a pic taken 10 years ago when he was about five months old (back before I started marking every pic!). That particular pic has been used on hundreds of websites and social media posts since then.

The second pic on the scam post is lifted from "The Total Axolotl" page.

The scammer's profile page is "Edmond Bush", an admin on the page "Axolotl for beginners USA and shipping" which is a straight-up scam page that uses pics lifted from other pages and websites.

This scammer has been reported many times. Facebook will not take the page down.

So let's have some fun :)

Let's be annoying as possible. Message "Edmond Bush" and try to buy Lokai the split mosaic from him. DON'T comment on the post, other than to ask him to message you with info. If you comment or message anything to suggest you know it's a scam you'll be blocked immediately!

Don't reveal that you know it's a scam, and see how long you can keep them busy.

DO NOT reveal any personal or financial information! This is a "scam gang" that will use any info they get to steal from you.

While you're at it, message anyone who comments anything other than "message me" on the scam post to let them know it's a scam. Then report both the group and the admin to Facebook as a scam, and maybe we can get both taken down like we did the last time we tried this :)

I'll send a Lokai refrigerator magnet (like the one in the pic below) to the person who can get the most replies from them between now and Sunday, 6 pm EST.

Here is the post on the scam page:

https://www.facebook.com/groups/965700208232487/?multi_permalinks=1175856220550217&hoisted_section_header_type=recently_seen&__cft__[0]=AZVXAUxjDBRvCC9U5zDKHsWYGQgvFjsZO2a0xIIXeWWgHqZ1lw5MdvvX8NJQ_sLxRTB1744IK95cXI1a7otLikkSsNaFHwmZ8YakkGytB73SN8gTzyOAliEV69zvGzsyoTX_cofWPi1NN3MgXkqSWHueAqj9tddPprOKf8XunKRW958i0RszYStrqthHHvBJX2u4ysdxMLJmDXvb8ECDSyma&__tn__=%2CO%2CP-R

Update (January 27, 2025): It worked! Not only did you all annoy the scammer, but Facebook has actually taken the group down!
Well done, and thank you all.

01/19/2025

Doors are open at the Indiana Reptile Breeders Expo! Come see us at the old Toys r Us location at River Falls Mall in Clarksville, Indiana until 4pm today.

01/16/2025

Strohl's Herptiles will be at the Indiana Reptile Breeder's Expo this Sunday, January 19, from 10 am to 4 pm.

This month's show will be held at the River Falls Mall in Clarksville, in what was once the Toy's R Us section.

We will have a stunning selection of axolotls, including s*xed adults and juveniles, fresh emu eggs for eating or hatching, as well as an ever-growing variety of unique custom-crafted terrarium decor for your dart frogs, crested geckos, and more!

01/06/2025

Taking some pics of the boys while waiting for the snow to end...
Thought they might brighten your day on this Arctic, Midwestern afternoon :)

01/03/2025

IRBE show on January 19th will be at Toys R Us building at the River Falls Mall in Clarksville Indiana! 651 e Lewis and Clark pkwy

Don't miss this one!

https://www.facebook.com/IRBExpo/posts/pfbid02reV3uo1RgoBXxTUJFRvKroaW79rAhX3VwW428aPcNk5kpqEW1TUfx69H2eYYMaX4l?__cft__[0]=AZVgGLezc6CrQo8PRfKjfAQKUj-7x0hpCgP3tAkIsfROWrx-QbKItoDzbevKxQbj5BcsskyQJZDNLXkkYYz9lbZkOzsOsdPJyNLviPlMe_rMw4A9xGhEBtPbgDTjo4Ys6dWXRhDGauhHhrtPisb1anxovZqqF-cb5QUhKZfrCGX9o5h2w8ASQHV51sIbgFZ7IIm1rLut9uYICp6Qq2OWvqjWO9W9foR1kV3RxUpxD1LVXFl5y4Fwjtm7xZA6LXVwLHpN7kT4uCu4Am33BDzVYCRp&__tn__=%2CO%2CP-R

Send a message to learn more

12/22/2024

I am, as usual this time of year, starting to see a lot of posts about “oops” axolotl clutches, begging for help and guidance after the event. Just as disturbingly, I see breeders post pics of tubs full of hundreds, if not thousands, of eggs and/or hatchlings. Not cool, people.

I get complaints that my posts are too long. A lot. I do try to limit the length of my posts, and honestly more gets left on the cutting room floor than I post. I feel I need all those words to clarify points and provide context, or I will be flooded with reams of “yeah, but what about…”, and “that’s only true if…”, and “you’re stupid”, etc.

But I get it: Many of you have been raised on soundbites, memes, Twitter (I will never say “X”), and TicToc. Punctuation, exposition, and clarification are not your thing.

So here is a severe edit from an old post (from April 10,2024) with all the extraneous stuff cut away::

…producing and distributing a large number of animals… is a problem. … inbreeding in the pet trade has increased with each generation. …with so many animals from desirable lineages flooding the pet trade it is inevitable that closely related animals will sometimes get paired.

When pet shops get a hundred babies from… an “oops” clutch, or someone… hatches an “oops” clutch because they don’t have the good sense or courage to do the right thing and cull the eggs, the odds that those animals are not the offspring of siblings or first cousins is pretty low.

(How) to reduce the problem?
(a) Produce smaller clutches, and
(b) Breed each animal only once or twice.

If you produce 500 babies from one clutch… there is a very high probability that some of those siblings are going to end up paired together to produce more in**ed offspring.

If… you produce only 50 offspring… the probability that any of those axolotls will be paired with their siblings or other close relatives is only one tenth as great!

If you hatch 40 and sell 460 (eggs), you're still producing 500 babies from the same pairing!

"But wait," you say, …”If I hatch only 50 eggs I may lose them all!" …you have no idea what you are doing and should stop doing it. …your survival rate with a clutch of 30 to 40 babies should be 95% or better.

Limiting any axolotl to just one or two clutches is a simple way to maintain some genetic diversity.

(Producing smaller clutches means) the breeder is raising... fewer, healthier offspring, and can therefore command higher prices. Producing fewer offspring per clutch and per adult axolotl benefits the axolotls, the breeders, and the pet owners. Everyone wins!

12/21/2024

Help annoy a scammer and win a 2024 axolotl ornament!

Here's how:
1. Find "Axolotls available in USA".
2. Scroll through the posts, and find some really cool axolotl you MUST have. They're ALL stolen from other sites, including Strohls Herptiles - and, of course, there's a pic of Lokai in there, too :)
3. Comment on the post if you want, but to make this work, you must message them for information. DON'T let them know that you know it's a scam! They will block you immediately.
DO NOT give them ANY identifying information about you at all.
4. Take screenshots of your messenger conversations and comment them below.

Whoever can keep them busy the longest gets a free 2024 axolotl ornament :) Contest ends on Christmas Day (Dec. 25, 2024).

I've already had them going a while, and I'm not really even trying. Even dropped obvious hints that I'm playing them. I offered to buy some "firefly" axolotls - animals that I produced here many years ago - and was offered a really excellent price. SHIPPED! BY CHRISTMAS!

I'll post my screenshots in the comments below.

Update (12-24-2024):

This particular scammer page has been taken down as of today, the contest is over, and we all won 🙂

The clear winner of the contest with more than 30 screenshots and 60+ unique responses is Paris Cannon!

A sincere THANK YOU to all who participated.

12/17/2024

As you may know, I don't pair axolotls until later in Winter, so stocks are getting low this time of year, but A few wilds and mixed (het axanthic and copper) hypomelanistics produced for test crosses will be available in January.

https://sites.google.com/view/strohlsherptiles/home/available-axolotls

12/15/2024

Join us at the IRBE show tomorrow, Sunday at the S&S Marine Building at 1407 Emery Crossing Ln, Clarksville IN from 10 am to 4 pm.

If you want an exceptional axolotl this Christmas, this is your opportunity!

12/14/2024

The first of this year's emu eggs will be available at the Indiana Reptile Breeders Expo in Clarksville this Sunday!
That's a large chicken egg in the middle for comparison.

The female is "blonde", so half of these eggs contain blonde embryos. It's up to you to incubate them.

The outside is a deep forest green, while beneath the surface is a pale green-teal layer, and the interior of the shell is snow white. Emu eggshells are often used by artists and craftsmen because of their distinctive colors and textured surface. Artists etch or carve into the shells to create a three-dimensional look.

Of course, they also make amazing omelets :)

12/11/2024

I'm finishing up the last of the 2024 Christmas ornaments to take to the Indiana Reptile Breeders Expo at 1407 Emery Crossing Road, Clarksville, IN, on Sunday :)

12/10/2024

All of the GFP Copper Leucistics are now old enough to s*x. These and many others will be available at the Indiana Reptile Breeder's Expo in Clarksville, Indiana, this Sunday.

12/02/2024

Columnaris infection?

I’m frequently contacted by people with sick axolotls. Most of the time they are simply dealing with minor infections brought on by stress, injury, or poor water quality, all of which have easy fixes that often require no major medical intervention.

Now and then, though, I see something more serious. Over the last few weeks, I have been contacted by multiple people with very sick axolotls, usually with the following symptoms in order of appearance:

- Reduced appetite over several days (and maybe much longer).
- Reduced activity and attentiveness.
- Reduction of gills, which may include reduction of gill filaments and shortening of the gill stalks (rami).
- White, fuzzy patches on the head and body.
- Short, white stringy material on the lips, gill stalks (rami), and later coming from the white patches on the skin.
- Peeling skin.
- Bleeding from sores on the head and body, especially when touched or after thrashing movement.
- Death.
Note; Bloating is a common sign of late-stage infection, but may not occur in all infected axolotls.

While a lot of different bacterial and fungal infections can cause the first 3-4 symptoms, only one disease causes all 8: Columnaris.

Columnaris is a bacterial disease caused by Flavobacterium columnare (identified in older literature as Bacillus columnaris, Chondrococcus columnaris, Cytophaga columnaris or Flexibacter columnaris). It is a rod-shaped, Gram-negative bacterium that is common and often abundant in warm, freshwater environments. The name is descriptive of the column-like (or thread-like) structures you see under a microscope. It can infect a wide range of freshwater fish and amphibians, including axolotls.

Columnaris is an opportunistic pathogen. This means that it is pretty much always around in natural environments at low levels, but can’t cause illness unless some other illness, injury, or stress weakens the animal’s immune system. It then enters the body through an open wound or damaged skin.

An axolotl can sometimes live for years with a columnaris infection. The bacteria only cause severe disease when the axolotl is weakened or environmental conditions are especially favorable for bacterial growth, allowing the bacteria to overwhelm the axolotl’s immune defenses.

Columnaris primarily infects soft tissues such as the skin, gills, and mouth. The bacteria gain entry through abrasions, ulcers, or other weakened areas of the skin. Once inside, they produce enzymes that break down tissues, leading to visible signs like white skin lesions, oral ulcers, and peeling skin.

Left untreated, a columnaris infection will spread through the body. The bacteria eventually invade internal organs, leading to systemic infections causing severe damage to internal tissues and organs. This usually causes death from organ failure within a few days of obvious symptoms.

The white lesions on the skin also shed huge numbers of new columnaris bacteria (which is what the white, stringy stuff really is) into the surrounding water. At later stages, when the kidneys and intestinal lining are infected, bacteria are also shed in their waste. The high concentration of bacteria in the confined space of the aquarium dramatically increases the probability that otherwise healthy axolotls in the same tank will also get infected.

Edit: Be aware that it can be harder to see infections on lighter animals, particularly hypos with light skin and spots. It is always best to assume that if a dark animal in the tank is infected, they all are.

Once a columnaris infection is detected, immediate steps must be taken to save the axolotls.

Immediately quarantine the infected animal, and any other axolotls in the tank, even if they appear healthy. Columnaris is highly contagious, so it can spread through direct contact with infected individuals, contaminated water, or shared equipment. Also keep in mind that other aquatic organisms in the tank, such as guppies and even snails, will also be infected.

Tub each axolotl in cool water, treated to remove chlorine (as always!). The lower the temperature, the better, ideally about 50 F (15 C). In fact, this is one of the few times I recommend refrigerating an axolotl. Cold water slows the reproductive rate of the columnaris bacterium, allowing time for the axolotl’s immune system to build up a defense. Just make sure the refrigerator is not set below 40 F (5 C). Keeping them very cool also allows more time to obtain proper medication or schedule veterinary care. You don't need to keep them refrigerated after antibiotic treatment begins.

Tub each axolotl individually so that they can be medicated and monitored. Keeping them apart reduces risk of further stress and reinfection. It also allows you to keep track of which ones are eating, and when. Use a tub large enough to keep the axolotl safely submerged and wide enough to allow comfortable movement, since treatment is going to take 5-7 days, if all goes well.

When the tub is not actually in the refrigerator, add a bubbler (airstone) to each tub to increase oxygen levels. Columnaris damages skin and gill filaments, which reduces the axolotls' ability to absorb oxygen from the water.

Now for the treatment:
Whenever possible, get to an exotic veterinarian or aquatic specialist for a precise diagnosis and prescription as soon as a columnaris infection is suspected!

The critical, life-saving treatment is ANTIBIOTIC THERAPY.

The recommended antibiotics are:
Kanamycin. This is available in the USA as Kanaplex.
Oxytetracycline. Available as Aqualife Oxytetracycline.
Nitrofurazone and furazolidone. This used to be available in Furan II, but I don’t think it is sold anymore. An exotics vet or aquatics facility will have this on hand.

Edit: More experienced aquarists have suggested adding metronidazole in combination with kanamycin or nitrofurazone. This approach should be more effective since these meds attack the columnaris (and other Gram negative bacteria) in two different ways, which reduces the probability of resistant strains surviving the treatments. Metronidazole is available in Seachem MetroPlex and Fritz MetroCleanse, among other commercial sources.

Follow the veterinarian’s or package instructions carefully regarding dosage and treatment duration. Continue treatment for 5-7 days EVEN IF SYMPTOMS SEEM TO GO AWAY! Stopping too early may leave the more antibiotic-resistant columnaris bacteria alive. They can then re-infect the animal, which means the next time you try to use the medication it won’t work!

For localized skin ulcers you can apply a dilute antiseptic such as povidone-iodine or methylene blue using a cotton swab. There used to be a product called RidRot that was good for this, and it may still be available in some areas. Don’t be surprised if this causes bleeding. Rinse off any residue before returning the axolotl to its tank.

I do not recommend salt, tea, or methylene blue baths. These can further irritate damaged skin, and can cause serious harm if done too frequently or at too high concentrations. Besides, there is no evidence whatsoever that any of these will stop columnaris, and at least a couple of published studies stating clearly that they do not!

While the animals are being treated, STERILIZE EVERYTHING!
Proper disinfection of equipment is critical when managing an outbreak.

Some aquarists who work with fish may think my approach is overkill, but in my opinion the inconvenience of complete sterilization, including all filter media and substrate, is trivial compared to the potential death of the axolotls and risk of infection of others. And yes, you will have to get the nitrogen cycle established all over again after the cleaning is done. Again, that is a small price to pay to protect your animals.

If you have never seen a columnaris infection, that’s awesome. If you never want to see one, avoiding these conditions dramatically reduces the likelihood of a columnaris outbreak:

1. Warm water (above 70 F):
Columnaris bacteria can survive and reproduce at any water temperature, but grow exceptionally well in warm water, and absolutely thrive between 25–30°C (77–86°F). This is one of many reasons that maintaining a cool environment for axolotls is essential. Axolotls have evolved in relatively cool, snow-melt and spring-fed lakes that naturally had a very low concentration of these (and other) warm-water bacteria, so their immune systems have lost much of their ancestor’s ability to fight off these types of opportunistic pathogens. If they are held in warm water, the high levels of columnaris bacteria can simply overwhelm them.

2. Poor Water Quality. We axolotl people are constantly preaching this:
High levels of ammonia, nitrite, or nitrate stress axolotls and compromise their immune systems. Ammonia and nitrite should never be above ZERO when water is tested between feedings. Nitrate should never be allowed to exceed about 40 ppm. Exceptionally hard water is also favored by columnaris bacteria, so check periodically and keep GH between 7–14° (125-250 ppm).

3. Stress:
Just like humans, axolotls don’t handle constant stress well. Overcrowding, frequent handling, constant noise/activity, and aggressive tank mates cause the release of stress hormones that push the immune system to its limits, making axolotls more susceptible to disease.

4. High bioload/low dissolved oxygen:
It is not so much that the bacteria prefer these conditions; It is that these conditions weaken the axolotls. Always clean up uneaten food and visible p**p before it decays. The bacteria feeding on these organic materials pull oxygen from the water, weakening the axolotls. They also produce ammonia, which among other things will burn skin, leaving the axolotl open to infections.

5. Nutritional Deficiencies:
A lack of a balanced diet - particularly a lack of protein - will impair immune function and healing ability.

6. Introduction of an infected animal:
This is a big one! ANY new animals should be quarantined in isolation for AT LEAST 14 days under observation to watch for any sign of infection or parasites. I actually quarantine for a month or more before I risk introducing any new animal to a community tank.

I wrote this quickly and without much proofreading, so please let me know if anything seems off or needs clarification. Hope it helps.