This care guide is for the Arizona Mountain King snake (Lampropeltis Pyromelana), and is based on my own experiences with having kept mine thriving for over 10 years now. It also includes the research done on this species over that timeframe. My reasoning for making this is to create as complete of a caresheet anyone could need for this species when looking to keep them as a pet.
15-20 years on average, can live longer with proper care.
18-41 inches, with males generally being smaller than females. Hatchlings are 8-12 inches depending on how big the mother was. Ammon was probably around 8 inches when I got him.
Experience Level: Intermediate.
Can’t get much hardier, 0 health issues experienced with mine over his life thus far.
Babies can be flighty and may musk/defensively bite, but many calm with consistent handling. Adults are easy to handle but are quite fast, not for kids but fine for responsible teens/adults. Please never consider this as a pet for small children, as they are fast and more fragile than one may realize.
Some care guides will say to give these guys a thermal gradient with a 90°F hotspot. Only do this if you want them to either hide and never eat, or just die. They can be kept on ambient temps in most cases. Daytime temps can be between 75-86°F, with the higher being the first couple days after they feed. Nighttime drops can be anywhere from 60-70°F without it bothering them at all. Make sure to give them a 10°F nighttime drop, and never let it get higher than 86°F. They can basically be kept like many Asian rat snakes, minus the humidity. These guys do not need extra humidity. Max humidity in my house is around 50-60%, and that is for a couple months in the summer. Any higher and I would need a dehumidifier for him. 40-50% humidity with spikes up to 60% for short durations is all they will need. Any higher and you risk RIs.
Many will say you don’t need a large enclosure for these guys, and an adult male will do fine in a 10 gallon. They also say they are terrestrial and don’t climb and therefore do fine in tubs. I will say those points are completely wrong if you want this species to truly thrive. A 20 gallon or equivalent is the bare minimum I recommend for a male. 29 gallons or equivalent is what I recommend for a female. I have kept my male in an exo-terra that is 18x18x24 his whole life and he takes advantage of every inch. He especially likes spending time on the higher areas of the tank. If you use a tank insert, make sure that they 100% cannot get behind it. The juveniles are extremely small, and very good at getting into/out of things. This goes for their tank as well. They will escape if you don’t make sure it is secure. If you can fit the tip of your pinky into it, then it isn’t secure.
They are mountain dwellers in nature, and while they may not climb many trees, they do climb rocks and things of the sort in search for food. They are active and an amazing display species. They thrive with being able to explore and search around in things. This species does not need humidity, and would not be ideal for dusty substrates either. Given their small size impaction is also a risk with small particulates. This species is not adapted for burrowing and doesn’t need to, as their native range is made up of compacted dirt and rocks. Large branches, rocks, perches, fake vines, half logs, a couple enclosed hides, tubes from paper towel rolls, can all be used in a setup for this species. A small shallow water bowl will be fine for them as well. You can make a really fancy mountain-themed terrarium for them, and they will enjoy it. You can use reptile carpet and the like, but I find rubber backed mats like this work really well, so long as you keep up with good spot cleaning. All you need to do is cut the size you need. This stuff holds onto a lot, so when I say it needs a thorough washing each month, I mean it. A scrubbing brush, soap, a water hose (the one attached to your sink will work fine if it is cold outside), and a reptile safe disinfectant used until it rinses clean. I have used the same piece for many years and it works wonders. It does take a few hours to get dry unless you use a good towel and blow-dryer, however. Be sure to have a temporary holding enclosure like a tub for your AMK if you go this route.
Feeding/Getting hatchlings started:
Feeding for this species is generally pretty simple. An appropriately sized mouse when they are juveniles once a week, spaced out to every ten days once subadult, then finally every two weeks to once a month as adults. Due to this species primarily being lizard/snake eaters in the wild, they can get fat very easily on mice and thus need longer breaks between feeding. This is especially true for adults. Multiple small prey items is also better than 1 large prey item. These guys can’t stretch their mouths as much as a python or boa, so never go slightly larger than the largest part of their body. Always the same size or slightly smaller than the widest part of them.
Now, nine times out of ten your hatchling you get from a breeder will be well started on mice. If they aren’t, the breeder will tell you what they eat and what to do in most cases. Even when I got my boy over 10 years ago in a local pet shop, he ate pinkies no problem. However, sometimes breeders just don’t care and never properly start their hatchlings or tell anyone otherwise. There are a few things you can do thankfully. First, I have always put my AMK in a box to feed him. When he was very small and scared of the world I would put a f/t pinky in with him and close the box. I would wait for 30 minutes and he would always have the pinky down by then. Now, I still feed him in a box, but he takes his food from tongs. I have used tongs since he was around a year and a half old and comfortable with me. To get a picky hatchling started, you may need to try a couple of things. Scenting a pinky with lizards, frog scent, or even a shed skin from another snake you own can all be tried first. Use the closed box method when doing this as well. If that doesn’t work, a f/t feeder lizard like a house gecko or anole is your next step. You can also try some iguana reptilinks. It is rare for them to refuse a feeder lizard. I recommend f/t especially for anoles because almost all you get will be wild caught and risk giving your snake parasites. You can slowly transition them to pinkies over time with scenting, and having one refuse food once it is well started is unlikely. Mine has never missed a meal. They are king snakes, so they really like food. Figuring out which food can sometimes be tricky however.
I personally brumate all of my North American native snakes, and have always brumated my AMK as well. This means you take them off feed for a few weeks to make sure they are empty, and then you keep them off food for 2-3 months while it stays cooler in their enclosure. Always make sure they have access to water during this process. It stays cool enough in the room I keep them in the winter to brumate them, but sometimes you need to put them in a tub and use a small refrigerator to cool them if you live in a sub-tropical area.
I don’t worry about length or weight gain as much as just body condition. If they look a good weight, not overweight or underweight, then you are feeding them just fine. They are a very small species and are naturally slim, even at 2’6" my AMK at his widest is no thicker than a nickel at the most. Just make sure to never over feed them as that will shorten their already relatively short lifespan. If your male at 3-4 years old is only 20 inches, don’t worry. Adult males are small things, and one over 3 feet is rare.
If anyone has questions about AMK that isn’t covered in this care guide, please don’t hesitate to ask! Sorry it took so long to get this done to those who were waiting as well!