4 Reasons Why Iguanas Turn Black: Solutions Included

why is my iguana turning black

Although iguanas cannot change into a completely new color, they can indeed change into lighter or darker shades of their original color in order to better adapt to their environment. In certain occasions, an iguana will get really dark, almost making it look black.

As a general rule of thumb, stress, anger, cold temperature, and disease include the most common reasons why iguanas turn black. Taking immediate action to determine why the iguana’s skin has turned black is highly advised, as some of the causes can result in death within a matter of minutes.

Below are the four most common reasons why your pet iguana’s skin may turn black, and what to do about it.

1 Your Iguana is Stressed

Your Iguana is Stressed
Stressed Out Iguana

According to Melissa Kaplan, the darkening of the skin is often caused by extremely stressful situations, which can sometimes be easily resolved. 

Short-term stress won’t kill an iguana. However, the symptoms induced by chronic stress can be detrimental to their health. Hence, try to determine the stressor as quickly as possible.

To confirm if stress is the culprit, look for additional signs such as:

  • Decreased appetite
  • Hiding
  • Digging
  • Persistently attempting to escape
  • Shedding issues


The following are common causes of stress. If you manage to identify any of the reasons below, do your iguana a favor and remove the stressor from its environment.

  • Loud noises
  • Too small of an enclosure (addressed in more detail below)
  • Unsanitary environment (feces should be removed daily)
  • Changes in the environment
  • A new companion in the same enclosure
  • A new pet
  • A new person
  • Being handled incorrectly

Enclosure Size: Regarding the size of the enclosure, remember that iguanas can grow as long as 6 feet SVL (snout vent length), and as fast as 3 feet by the time they’re 1.5 years old.

Therefore, a terrarium should only be used to house hatchlings for their first couple of months. Adults require a cage measuring at least 8ft long by 8ft high by 4-6ft wide.

For more info on angry stressed, check out this post I wrote: 15 Signs of a Stressed Iguana & What to do About it

2 Your Iguana is Angry

Your Iguana is Angry
An angry iguana will turn black, position itself sideways, and puff their dewlaps

Although both anger and stress will cause an iguana to turn black, an angry iguana will display a completely different set of behaviors.

For safety reasons, learning to adeptly recognize signs of aggression should be one of your top priorities.

An angry iguana is likely to feel threatened and show signs that its ready to attack. You can differentiate stress from anger via the following signs:

  • Stands sideways to look bigger
  • Puffs its dewlap
  • Hissing
  • Tail whips
  • Bites
  • Keeps its mouth open 

Check out this post about iguana bites to learn how to identify and fix their aggressive behavior. It may save you a trip to the hospital.

Examples of angry iguana behavior


Always be careful when handling an aggressive iguana, especially adults, as they can cause serious injuries.

The following reasons may be angering your iguana:

  • An aggressive iguana in the same enclosure
  • A new pet
  • A new person
  • Mating season

As I recommended with stress, simply remove whatever is angering your iguana from its environment and allow it to calm down.

Check out this post I wrote to learn more about angry iguanas, as they can be quite aggressive sometimes.

3 Your Iguana is Cold

Your Iguana is Cold
One of the most common reasons for iguanas turning black is the cold

Because iguanas are ectothermic (cold blooded) creatures, they obtain their ideal body temperature via a process called thermoregulation.

In the wild, iguanas thermoregulate by moving in and out of the sun. However, in captivity, the sun is substituted with a heat lamp, which is placed above their enclosure.

Failure to provide your iguana with a a temperature of at least 85 degrees (29.4 Celsius) will result in the inability to digest its food and ultimately, death.

In fact, if the temperature in the enclosure falls beneath 40 degrees (4.4 Celsius), your iguana will die within a matter of minutes.

Forest Wildlife explains that iguanas turn black because it’s the best color for absorbing heat. Hence, if your iguana is black and feels cold to the touch, cold temperature may be the culprit.


Invest in a heat lamp and thermometer as soon as possible, as iguana’s need a basking spot to maintain their proper body temperatures.

The basking spot can range from 96-100 degrees (35.5-37.7 Celsius) while the cooler side of the cage should reach 78-80 degrees (25.5-26.6 Celsius).

The heat lamp should be placed roughly one foot away from the basking spot, but keep an eye on the thermometer to find the exact distance. 

An iguana reverting to its original color after warming up

You can also protect your iguana from cold temperatures by insulating the cage with additional substrate. 

Artificial grass, paper pellets, and other pet-safe substrates can be added to an iguanas cage to provide comfort and increase warmth.

Keep in mind that extreme heat is just as threatening to your iguana as severe cold. If the air temperature in the enclosure reaches 113 degrees (45 Celsius) your iguana will die.

4 Your Iguana is Sick

Your Iguana is Sick

When an iguana is sick, it is very likely to turn black. However, additional signs of a sick iguana may include:

  • Lethargy
  • Abnormal feces
  • Loss of appetite/weight-loss
  • Vomit
  • Loss of balance
  • Twitching
  • Sunken eyes

There exists a wide range of diseases which iguanas can contract. The most common include:

  • Salmonella
  • Tail rot
  • Mouth rot
  • Parasites
  • Metabolic bone disease (addressed in more detail below)


If your iguana is sick, it’s absolutely crucial you pay a visit to the vet, not only for the iguanas survival, but also for your safety, as some diseases can be contracted by humans, such as Salmonella.


By providing proper care and diet, you can avoid the vast majority of medical problems.

Don’t wait until things have gone horribly wrong. Take your lizard friend to the vet every year for annual checkups.

You can also minimize the transmission by maintaining your iguana’s enclosure in sanitary conditions.

MBD: Unlike the other diseases, Metabolic bone disease is not transmitted. It’s caused by a calcium deficiency, which can be prevented with proper lighting.

According to iguana expert, James W. Hatfield in his book, Green Iguana The Ultimate Owner’s Manual, your iguana should be receiving 12-14 hours of UVB light exposure on a daily basis.

He also recommends a bulb that emits both UVA and UVB, such as the Lucky Herp Light, which is currently one of the most popular and best priced bulbs in the market.

Click the link to be redirected to a guide I created not too long ago regarding the signs of a healthy iguana.

How Long Before My Iguana Goes Back to Its Original Color?

The answer to this question is going to depend on the reason why your iguana turned black in the first place.

However, most of the time, your iguana should revert to its original color within the same day, especially if anger, stress, or cold were responsible for the color change.

If your iguana is sick, it may take a few days, but more than likely weeks, before you see its beautiful green color again.

What Color is a Healthy Iguana?

what color is a heathy iguana
A healthy iguana is usually a vibrant green color

As a general rule, healthy iguanas are a vibrant green color, with a bit of yellow and orange, especially during mating season. A healthy and happy iguana will be more vibrant than its stressed or sick counterparts.


Phillip is the proud founder of Scaly Pets, a website dedicated to educating reptile pet owners. As a former owner of various reptiles, Phillip not only brings well researched topics to the table, but also years of personal experience. Now, he's sharing his passion with the rest of the world.

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