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tortoise skin darkening

Tortoise Skin Changing Color – Why It Happens!

A tortoise that changes color in patches, especially over a relatively short period of time, usually has a disease, sickness, or infection.

However, there are times when a gradual full-bodied color change is normal. So, note what color your tortoise is changing to and if it’s acting differently or strangely.

Skin slowly darkening or turning black is a natural sign of aging. If the skin darkens in patches, the substrate is unclean or a source of irritation.

If your tortoise’s skin is turning white, it’s shedding its skin or has an infection.

If the skin turns red, this can mean parasites (ticks or mites). If there’s a red fluid below the scutes, this indicates shell rot. If your tortoise’s skin turns yellow, this can be due to poor diet, liver failure, or jaundice.

You can avoid some skin conditions in tortoises by maintaining a clean tank.

Also, according to the Australian Veterinary Journal, setting up the tortoise’s enclosure with a soft, moist substrate and warm internal temperatures is highly recommended.

Tortoise Skin Turning Yellow

If your tortoise turns yellow suddenly, check for these conditions:


This is a skin condition that is caused by instability in the liver.

Jaundice can occur in three ways:

  • Obstruction of the bile duct
  • Liver disease
  • Excessive breakdown of the red blood cells in the liver

These will cause the skin to turn yellow.

According to the Association of Reptilian and Amphibian Veterinarians, liver disease can be difficult to diagnose in tortoises until its symptoms have become severe.

Liver Failure

Alongside jaundice, which is a symptom and an issue of its own, your tortoise may have acute liver failure.

The tortoise turns a sickly yellow and:

  • Suddenly becomes lethargic
  • Fails to eat its meals
  • Avoids moving around, even to bask

Other signs of chronic liver disease include:

  • Reduced weight gain or significant weight loss
  • Brumation issues, including post-hibernation anorexia
  • Changes to the color of the skin and fecal matter

Poor Diet

Your tortoise may have too much fat or protein in its diet. In fact, degenerative liver disease is usually caused by poor nutrition and chronic fat changes.

Correcting your tortoise’s diet is always recommended. You should allow your tortoise more time to bask under UV light, as this can boost its metabolism and immune system.

Tortoise Skin Turning Black

When you see a tortoise’s skin turn black, it’s natural to assume the worst. However, tortoises rarely get gangrene or other serious conditions responsible for blackening skin.

Here’s what causes tortoises to turn black:


A natural reason for tortoise skin darkening is age. If your tortoise used to have a lighter carapace or skin, which darkened over time, this is a sign that you’re taking good care of it, and it’s aging as it should.

Some tortoise species, including the Russian tortoise, will have a naturally dark pigmentation to their skin, and this will intensify as they get older and may appear to turn black.

Irritation From Bad Substrate

This darkening skin should occur all over the tortoise’s body and not be centralized to one area. If you see only the underside of your tortoise starting to darken, it may be irritated by the substrate in its enclosure.

All tortoise enclosures should have a non-toxic substrate that can be safely ingested without harming its digestive tract. This substrate should retain moisture so that the skin doesn’t dry out and flake off.

tortoise skin infections

Infection From Substrate

If you fail to clean out the substrate, your tortoise is more susceptible to infections, and these can manifest as darkened irritations or abscesses under its carapace.

Abscesses need to be surgically removed, or you’ll risk pus and bacteria building up around the wound.

Tortoise Skin Turning White

Of the different tortoise color changes, whitening skin is the most common, naturally turning white every few months.

Here are the causes of white skin in tortoises:


If your tortoise’s skin fades to a lighter color or turns white, this can mean it’s preparing to flake off.

As with all reptiles, tortoises shed their skin every few months to allow for new growth. However, this won’t happen in large strips or all at once like a snake. Instead, tortoises shed their skin in patches.

If you see any flaky white parts on your tortoise, this is excess skin. Don’t pick off these flakes, as doing so could harm your tortoise.

If you’re concerned about skin flakes, give your tortoise a light bath in shallow, warm water. Also, allowing your tortoise to bask under UV light more often can dry out its old skin and allow it to flake off.

A tortoise will shed parts of its shell, and they’ll start by losing color and making your tortoise’s shell appear duller than before. Let your tortoise shed these parts naturally.

According to the Smithsonian Museum, these discarded scutes will leave behind rings like those on a tree, so you can estimate how old your tortoise is based on them.

Skin Infections

There are cases when white skin indicates an infection or fungus growing on its skin or shell. The best way to tell the difference between these conditions and shedding is by monitoring your tortoise’s behavior.

A tortoise in the process of shedding won’t show any signs of distress or lethargy. Shedding tortoises may bask more often, but otherwise, they should eat, drink, and play around in their enclosure as usual.

If your tortoise has an infection, it will:

If your tortoise has a fungal infection, this can appear as white or gray along the skin.

If left unattended, it can lead to shell rot, which is dangerous for tortoises.

Red Markings on Tortoise

If you see red fluid directly underneath the scutes of the tortoise’s shell, this can be a sign of shell rot.

However, this red fluid isn’t enough to cause your tortoise’s skin to turn truly red. Indeed, prominent red markings usually indicate parasites.

Tortoises turn red for these reasons:

Shell Rot

Shell rot is a condition that usually affects older tortoises more than adolescent ones.

This can occur from bacterial or fungal infections and is particularly dangerous. Shell rot causes the shell to slowly deteriorate and other health conditions.

Shell rot can be caused by a lack of certain nutrients, such as calcium or phosphorus, in its diet. Typically, bacterial, fungal, or algal infections damage the shell the most. These infections can get under the carapace, attack your tortoise’s skin, and poison its bloodstream.

This blood infection is called septicaemic cutaneous ulcerative disease (SCUD). Bacteria in the blood can attack your tortoise’s vital organs, which can be fatal. This can be countered with antibiotics.

New owners may not recognize these symptoms until the tortoise becomes very sick.

The warning signs include:

  • Unpleasant discharge or smells concentrated around the affected area
  • Reddish fluid under the scutes of the shell
  • Softening, lifting, or otherwise negatively impacting the carapace and the scutes

If your tortoise’s carapace starts flaking off, clean it twice a day with a povidone-iodine or chlorhexidine solution. Even if the tortoise is shedding, this can remove its old skin faster without any issues.


Red markings on your tortoise can indicate ticks, mites, or other external parasites.

Unfortunately, ticks and mites cluster where your tortoise’s skin is the thinnest. That’s why most will develop small lesions or cuts around these areas. Then, parasites will then lay their eggs inside the cuts.

Ticks or mites tend to be black or red and so small that they’re hard to detect. They’ll burrow themselves in or around your tortoise’s upper legs, neck, head, or other crevices that are hard to reach.