Trioceros johnstoni

Male Johnstoni

Banner image courtesy of Marc Vaillant

Trioceros johnstoni Care Summary

To download the Trioceros johnstoni care summary on a .pdf click on the image.

The Trioceros johnstoni Care Summary distills the most important aspects of husbandry care into an easily referenced handout. But chameleon care is, unfortunately, much more involved than can be presented on a summary sheet. Therefore, you may use this sheet as a reference and return to this page where we will go over each and every aspect that is on the summary sheet in detail.

Trioceros Johnstoni (Johnston's Three Horned Chameleon) Natural History

In the highlands of the mountain ranges that run down the borders of Uganda, Congo, Rwanda, and Burundi, from 1000 to 2400 meters above sea level we encounter a colorful three horned species, Trioceros johnstoni. Across this wide range we end up with four distinct color forms identified by their location: The Bwindi, Rwenzori, Congo, and Burundi. The Congo form is known in Europe as the “graueri” form taken from an old subspecies designation from the early 1900s.

Although the different forms have been exported before, the most commonly met are the Bwindi and the Rwenzori locales with the Bwindi tending toward the blue colors and Rwenzori towards the red colors.

Range map for Trioceros johnstoni
Marc Vaillant
Bwindi Impenetrable Forest

The Bwindi Impenetrable Forest in Uganda. This is the habitat of Trioceros johnstoni. Image by Marc Vaillant

Marc Vaillant is a wildlife, and especially reptile, enthusiast who has travelled around Africa for both work with the UN and pleasure. On a recent trip to Uganda he visited both Mt. Elgon and the Bwindi Impenetrable Forest. He shared this about his experience with T. johnstoni:

These were found on the edge of the Bwindi Impenetrable Forest Reserve. We only found two individuals (two males boasting rather different coloration).

Sadly, I’m not sure about the exact altitude, but this is obviously also an area that experiences significant temperature gradients. Rainfall and mist are also the rule rather than the exception.

While we were mostly there to observe the famous Mountain Gorillas, johnstoni was naturally also high on the list. We immediately enquired about chameleons among the locals. Unlike around Mount Elgon, the communities here seemed more warry about chameleons. They seemed to fear them and kept their distance once we found one. Regardless, a bunch of friendly kids took us on a walk along a dirt road next to their village, explaining that it would be a good spot for chameleons. Surely enough, we quickly found the two individuals you see in the pictures, only a couple hundred meters from one another. Both were found mid-day in low trees/bushes on the edge of the road. Both seemed to be enjoying some rays of sun in what had otherwise been a cold and misty morning.

Interestingly, some locals told us that the chameleons of the area were in decline. They cited an increase in predatory crows/ravens as the responsible cause. Whether there is any truth in that, I don’t know.

Trioceros johnstoni

A Male Trioceros johnstoni. Bwindi locale. Image by Marc Vaillant

Male Trioceros johnstonii

A Male Trioceros johnstoni. Bwindi locale. Image by Marc Vaillant

Captive Husbandry

Jurgen Van Overbeke is a chameleon breeder in Belgium who has extensive experience with a wide range of chameleon species. He offers his insight into breeding and keeping Trioceros johnstoni.

Trioceros johnstoni is one of my favorites. With its color and horns it is hard to imagine a better combination. Not only are the males colorful with horns, but the females are beautifully colored as well.  

The care conditions are standard for this higher elevation species. Mild day time temperatures that don’t go above room temperature, but ensure they have a basking light if they choose to warm up. They definitely need that strong nighttime drop. Keep them in a densely planted terrarium and do not keep them together. This species does not have much of a tolerance for each other.

For hydration I gave them around three hours of fogging in the very early morning before the lights came on and a 15 minute misting in the later afternoon. I then run a dripper just to make sure nothing is missed.

I provide them with natural unfiltered sunlight during the summer and a T8 Reptisun 5.0 during the winter. They are sensitive to supplementation so I give calcium once per week during summer and calcium with vitamin D3 once per week in winter.

Breeding is not complicated. Gestation is three months and the female lays quite large eggs that hatch in about 100 days when incubated around 18-21C (upper 60s F). Young females lay 12 eggs and larger females can lay up to 18 eggs. One clutch per year is standard, though I have a two clutch year before.

The babies hatch out surprisingly large and are easy to raise up.

Jurgen Van Overbeke

Listen to Jurgen introduce us to Trioceros johnstoni

Johnstoni hatching
Male Trioceros johnstonii
Male Trioceros johnstoni

Cage Type and Size

hybrid chameleon cage

The minimum cage size for both males and females that allows the creation of a suitable environment is 2’ x 2’ x 4’ tall, but males, especially, get to a size where a wider cage would be appreciated. Since they are comfortable in the 70s F , which matches our home comfort levels,  a screen cage is often a good choice for cage type, but to produce the high nighttime humidity a hybrid cage with three solid sides is more effective.

House males and females separately.

Johnston’s Chameleons are housed in the Forest Edge style cage interior.  A forest edge cage provides the open basking area and the densely leafy area where they can retreat, hide, and feel safe. This retreat area is critical for their well being. Notice in the cage shown here that there are distinct open and leafy areas. This is what a Forest Edge cage will look like. The most overlooked aspect of a chameleon cage is the visual retreat where the chameleon can hide away when they desire privacy. This is critical for creating an effective chameleon environment.

Ambient Temperature

Ambient temperature is what most of the cage will read. If you have a screen cage this reading will be suspiciously similar to your room conditions. The basking bulb creates a warm microclimate that will dissipate in a relatively short distance.

Basking Temperature

A low nighttime temperature is a requirement for a healthy Johnston’s Chameleon. But your chameleon will need to warm up in the morning to get a good start on the day. In the wild, chameleons look to the sun rise and bask until their body temperature is sufficient for optimal hunting, digestion, and general function.

In captivity we give them this warm up through a basking bulb which is usually an incandescent bulb shining on their basking branch.

We need to be careful when setting up this bulb as it is very easy to burn your chameleon. Chameleons do not seem to have a keen sense of when they are being burned. And this is the reason that we will be encouraging basking bulbs to be mounted above the cage instead of on the cage top. The closer to the bulb, the more difference in temperature can happen in an inch. The ideal scenario is to have a higher wattage bulb further away. This produces a wider, and “gentler” heated area that has no burn risk.

For temperature we are looking for something in the mid 80s. But the exact temperature is not that important. It is more important to set it up so you feel a warm and gentle heat on the back of your hand when you place it where the top of the head of your chameleon would be when he is basking. Your main purpose is to set up a safe temperature to start with and then you will adjust the bulb distance based on your chameleon’s behavior. If your chameleon shows the following behaviors, bring the bulb closer

  1. Huddling under the bulb for more than 30 minutes
  2. Hanging from the top screen panel under the bulb
  3. Remaining dark and lethargic. After basking, they should take on resting colors.

The issue with relying on behaviors as a signal to move the bulb further away is that they generally are physical damage to the body such as gray burned areas, open wounds, and melted back spines. And it is concerning how long this kind of situation goes on before the keeper realizes what is going on. So this means the chameleon is basking even though it is too hot. Thus it is better to start low rather than high. The mid 80s F is a safe range to start off with. You can even start at the low 80s if you would like to be cautious. But always do the back of the hand test and watch behavior.


Johnston’s Chameleons experience high humidity nights and mid humidity days. A nighttime humidity of 75% to 100% and then a drop to 50% during the day will allow them to engage in their natural humidity cycle. The exact numbers are not critical. There are two important aspects. 1) during high humidity times keep the air moving. Often cages are modified to enclose sides to impede airflow so a fogger can increase humidity. In this case have a ceiling fan or computer fan mounted to the top of the cage make sure that the “fog bank” circulates. Stagnant air, regardless of how humid, is unhealthy. 2) All surfaces must be dry during the day. Even if humidity is higher than the numbers listed, if the surfaces are dry then there shouldn’t be a health problem. It is when surfaces, such as the branches the chameleon climbs on are constantly wet the feet get sores and bacteria/fungus/mold is able to take a hold.


Johnston’s Chameleons take the standard bright light that we put on our chameleon cages. A quad High Output T5 fixture the width of your cage with four 6500K fluorescent bulbs will light a 4’ tall cage nicely. A 12 hours on and 12 hours off cycle is used.

Your chameleon will need it bright inside his cage. The biggest cage deficiency behind no hiding place, is insufficient light where, when you look at the cage, the chameleon looks like it is in a cave with a skylight. A bright cage will allow plants to grow and your environment to be vibrant.

Natural sunlight through a window is excellent, but use with caution. Sunlight tends to be too powerful and could overheat your chameleon. Be careful with sunlight. Note that sunlight filtered through a window will lose all UVB.


The most effective and reliable way to producing UVB for your chameleon is with linear T5 high output fluorescent tubes.

Presently we are targeting an UV Index of 3 at the basking branch with a maximum of UVI 6 to allow for sufficient vitamin D3 synthesis. This is generally what you can generate using a T5 HO Arcadia 6% or Zoomed Reptisun 5.0 in a single bulb reflector at a basking branch 6″  inches from the light going through a standard screen cage top panel.  These numbers are all general estimates as each reflector will have it’s own reflection properties and each bulb will have different strength depending on age. Luckily, this does not have to be an exact value. Ballpark is fine!

UVB Meters are an expensive piece of equipment, but are a valuable tool in setting up your chameleon’s environment. If you can get one – do it!

Setting up the lighting and hydration schedule

hydration cycle

When we set up our daily schedule we are attempting to replicate the wild conditions that the chameleon has grown to expect. Let’s start at midnight.

At midnight the chameleon has been asleep for many hours. It is dark and, although the moon waxes and wanes, chameleons will seek out dark places to sleep. They see light of all colors just fine and any light can disturb their rest.

As the early morning progresses the humidity rises. Fog banks can start to form and the chameleon is breathing in moist air. This high humidity forms an important part in their natural hydration. To simulate this, we turn ultrasonic humidifiers on around 1:30AM. The fog from the humidifiers tends to bounce off of surfaces and roll out the cage so we run the misting system for a couple of minute to coat the cage in a layer of water. This helps the fogger be more effective and the fog tends to stick around. The fogger go from 1:30 to 6:00 in a 30 minutes on and 30 minutes off pattern. This is to protect against too much fog. This is wise when you have closed in three or more sides of your cage to retain humidity. If you have a completely screen cage then you may leave it on the entire time. This all is done so the chameleon can breathe in the humidity. Just before the lights come on the misters are run for another couple of minute to make sure that when the chameleon wakes up it wakes up to surfaces covered in “dew”. This is a natural source of water for them even in their dry season. Once the dew is laid down the lights can come on.

Around 7AM the daylights come on. This can include the UVB light if they are the same fixture. If they are separate fixtures then save turning the UVB light on to correspond to when the basking bulb is switched on. I like to leave the daylight bulbs on for 15 or 30 minutes to give the chameleon a chance to leisurely lick whatever dew they want. I then turn the basking bulb on so they can warm themselves up.

As the ambient temperatures start to warm there is no longer the need for a basking lamp and it is shut off. The actual time that the basking lamp is on will depend on your chameleon’s needs. Watch the behavior. If the routinely get the warmth they need in 30 minutes and then climb away with content colors to hunt then reduce your basking time to that time that they make use of the warmth. If they need the warmth for a longer period of time then leave the basking bulb on longer or consider increasing the temperature slightly. Watch your chameleon and they will tell you what they need. With a screen cage there is usually no issue leaving it on for the day, but if your ambient daytime temperatures start getting to the high end of  their comfort, you can shut the basking lamp off.

Sometime during the day (I start at 3PM) start your dripper. This is a backup hydration strategy just to make sure they have enough water. While it is true they do not have drippers every day in the wild during the dry season, they also are not needing to reconstitute dry calcium powder on all their feeders. The advantage of running a dripper is that it is completely optional for them and, as a bonus, it also allows you the opportunity to ensure your plants get watered. Place it above a different plant each day and through out the week, all plants will get watered. It is not critical when you start the dripper. In this schedule I have it in the late afternoon so that the chameleon can rehydrate before the evening rest. I suggest starting the dripper an hour or so after feeding them so they can replenish what they need. In the wild, their food is a major source of hydration. We mess that up a bit with our powders and a dripper is a way we make up for that. Ideally, the chameleon will have gotten enough hydration from the moist night air, morning dew, and food items. I consider it a success when the chameleon ignores the dripper and an early warning sign when he drinks from the dripper.

Once the chameleon settles in and goes to sleep I like to have a couple minutes misting just to set up the night humidity.

You’ll notice there are no daytime mistings. Although this is common in chameleon husbandry, and I did it myself, I have transitioned my mistings to the sleep hours. Chameleons have been consistent in their communicating that they do not like being sprayed. I have given up deciding I know what is best for them and started to listen to them. The night fog, morning dew and the afternoon dripper provide the necessary hydration in a natural way. With those provided there just isn’t a need to force them into a shower in the middle of the day.


The job of the babies is to grow as fast as possible so as babies they should be fed as much as they can eat. Between 6 and 12 months old, reduce feeding to ten food items every other day. Thus is still a generous amount because Johnston’s Chameleons are still growing up to adult size during this time. Once they get to their adult size (around 12 months) you can take their feeding back to 3 richly gutloaded and supplemented food items every other day. Obesity in chameleons is a common and serious ailment.  Once it is obvious that the female is gravid, you can increase the food items to five food items every other day. Once her body has already determined how many eggs will be fertilized, then it is important to give her the all the nutrients necessary to create healthy babies. If she appears to be hungry after those five then it is okay to give extra. This is a period of time where she will need her nutrients.

There is often a complaint about chameleons refusing food or becoming very picky. The #1 reason why chameleons become picky eaters is because they are not hungry. We tend to feed our chameleons too much and once they are stuffed they only eat when it is their favorite food. If your chameleon refuses all but their favorite feeder then skip a meal and offer them one feeder of the standard type you wish them to eat again the next meal. You may skip up to a week without worry. In fact, two weeks is still not dangerous. As long as you offer the regular boring meal every couple days you will find their hunger point when it is reached.


Introduction to Supplementation and Johnston’s Chameleons

Supplementation is one of the least defined aspects of chameleon husbandry. We literally do not know what they need. We are guessing. The best we can do is try to get as close to their natural processes as possible and test regimens out.

There will be a number of approaches that work. The bottom line test is whether it produces a healthy, long lived chameleon. If it does then it is valid!

Trioceros johnstoni are especially sensitive to over-supplementation. They are prone to develop edema when the supplementation produces an imbalance. Therefore we must be extra careful to remove the fat soluble vitamins from the diet as much as is possible.

The Chameleon Academy Supplementation Approach

The supplementation routine chosen for our recommendation is designed to use be as close to nature as we can with what we know now. According to what we (think we) know, chameleons do not get a significant amount of vitamin D3 or vitamin A in their diet. Vitamin D3 comes from UVB and Vitamin A comes from…somewhere. We are still working out those details. Thus it is simple to know how to remove dietary D3. We provide sufficient UVB exposure. Removing preformed vitamin A from the diet is a bit tricky as some breeders can have generations of healthy babies with no dietary preformed vitamin A, while others will encounter birth defects, low survivability, and eye health issues unless preformed vitamin A is added. Thus, vitamin A remains a major hole in our understanding of chameleon nutrition. The most obvious suspect is the carotenoids within the gut loaded insects. Many animals use these to create vitamin A. A study done showed that beta carotene, the most commonly converted carotenoid in humans, was not, at least in isolation, converted by panther chameleons. More study will have to be done to determine which of (or if) the other carotenoids are being converted. But there is no known consistent source of preformed vitamin A in the wild chameleons’ diet. So it has to come from somewhere.


The Chameleon Academy supplementation schedule relies on 1) the presence of UVB in the strength of at least UV Index 3 for D3 conversion and 2) a rich gutload of feeder insects.

The Pre-Requisite of UVB levels at UV Index 3

The Chameleon Academy Supplementation Routine relies heavily on the chameleon producing its own Vitamin D3 from UVB exposure. This uses the natural body mechanisms designed for this purpose. This is highly desirable as vitamin D3 is fat soluble and can be overdosed and can cause serious health issues. Going through the natural process has a natural cut off where the body will stop producing D3 when it has enough. It maintains optimal levels in a way that we have no possible way of replicating.

The Pre-Requisite of Gutloaded Feeders

In all instances, feeders should be richly gutloaded with a variety of fruits and grains. They must be cared for with proper heat and even, we are learning, exposure to UVB. This creates the most healthy, nutrition packed feeder for your chameleon. Supplements are just that – a supplement to a properly gutloaded, healthy feeder insect. Supplements will not make up for a poorly fed feeder insect. Every supplementation routine requires a properly gutloaded feeder insect.

Supplementation for Every Feeding

Calcium will be given every feeding. Calcium is all around our world. Chameleons take in calcium through diet so this is the natural way they get it. And unused calcium flows through the digestive tract and out the other end so there is not a danger of overdose due to feeding too much calcium. Therefore we will dust each feeding with calcium.

The every feeding supplement should be, at least, plain calcium. I have chosen the Arcadia EarthPro-A supplement as the every-feeding supplement because

  1. No D3 and no vitamin A. Therefore there are no fat soluble vitamins to overdose or cause edema.
  2. Bee pollen ingredient. This “superfood” is a natural component in a chameleon’s diet. Although we keepers are generally panicked when a bee gets near our chameleon, do you notice how quickly they run over to eat it? They know they are getting good nutrition from this food item. (and, no, the stinger does not cause an issue in digestion)
  3. Rich carotenoids included. We do not know which carotenoid(s) chameleons use as their pro-vitamin A (what they use to create retinol – also known as vitamin A), but the special focus of EarthPro-A to include a wide variety of carotenoids without relying on Beta Carotene is our best option to work this problem out. If we are to remove pre-formed vitamin A out of the diet, EarthPro-A is the best hope of all the available supplements.

An alternative, if the Arcadia EarthPro-A is not available is to use bee pollen and calcium powder mixed together. Bee pollen does not stick on its own and mixing bee pollen powder with calcium powder or crushing up bee pollen granules with calcium powder will produce an effective (and well tested) every day powder supplement. If bee pollen is not available then the third choice would be to dust with plain calcium. Remember to get calcium without D3.

Supplementation Once A Month.

We have to be careful on this one as many manufacturers claim to have vitamin A, but what they really have is beta-carotene which is that carotenoid that we humans use to convert into retinol. We chameleon keepers have that study that, unfortunately, suggests that beta carotene is not effective for us. Though this study was done for panther chameleons. We do not know how similar chameleons from other genus are.  So you have to look at the ingredients list to verify that is really in there. I will be recommending the Repashy Calcium Plus LoD because it has both reasonable levels of vitamin A and Vitamin D3. While we really do not know how much vitamin A is safe, by using the lower dose we have a finer control over how much is being given if we have to adjust our dosage due to individual animal sensitivities.

Sensitive Species Supplementation

A nutrition regimen consisting of Arcadia Earthpro-A, Repashy Calcium Plus LoD, a UV Index of 3, and richly gutloaded feeder insects will provide nutrition for a chameleon over each of its life stages.

Chameleon nutrition requirements

Supplementation is just one component of the nutrition strategy. You must also have both a UV Index of  3 and feeder insects that are richly gutloaded for the Chameleon Academy supplementation regimen to work properly.

EarthPro-A Ingredients

The Arcadia EarthPro-A supplement was chosen as the every-feeding supplement because, in addition to calcium and basic B vitamins, it has bee pollen and carotenoids as major components. Bee pollen is a natural superfood while these carotenoids are the best chance we have of cracking the mystery of the vitamin A cycle in chameleons.

Calcium Plus LoD Ingredients List

Repashy Calcium Plus LoD was chosen for the vitamin A requirement because it is one of the few vitamin supplements that has vitamin A in the retinol stage (preformed) and not beta carotene which appears to not be effective in chameleons.


This seminar is part of the Johnston’s Chameleon Profile.

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