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Why Is My Tortoise Not Growing? (8 Stunted Growth Causes)

Last Updated on September 17, 2023 by Samantha Harris

Tortoises live long lives, growing much slower than other animals.

Depending on the species, a tortoise can take 5-10 years to reach its full size. Sometimes, a tortoise’s growth might slow down or stall, seemingly without explanation.

Most cases of stunted growth in tortoises can be corrected by adjusting their habitat, diet, and enrichment. These changes enable tortoises to physically grow and develop.  

What Causes Stunted Growth in Tortoises?

Some situations will cause a tortoise to grow slowly or stop growing. Some are caused by genetics, while others are caused by habitat or lifestyle. The causes of slow growth in tortoises include:

Cramped Enclosures

To grow healthily, tortoises need lots of space to walk around and explore. Movement allows tortoises to exercise and improve gut motility, facilitating better digestion and nutrient absorption.

Therefore, captive tortoises living in too-small enclosures with little room for walking and climbing will likely experience a slower growth rate than those with greater freedom.

Genetic Factors

Species like Kleinmann’s tortoise and the speckled cape tortoise are naturally small due to their genetic makeup. Any growth is likely to go unnoticed and be mistaken for stunted growth.

Some tortoises experience growth impediments due to genetic flaws passed on from previous generations. Unfortunately, there’s no way to address the problem if this is the case.

Unmet Metabolic Needs

Inadequate exposure to sunlight can impede the absorption of vitamin D3 and calcium, which are essential for bone, shell, and skeletal formation.

For this reason, captive tortoises must have a basking area in their outdoor enclosure and UV lights when kept indoors. This can help tortoises grow at a normal pace or prevent stunted growth.

Inadequate Diet

Most tortoises are herbivores, so they mainly subsist on plants and vegetation.

Of course, they’ll consume most non-toxic weeds, herbs, and leafy greens. However, the bulk of their diet should comprise fiber-rich and low-protein foods.

Provide nutritional supplements to ensure they receive other nutrients they may not get from their regular diet. For example, calcium supplements promote healthy bones and shell growth.

According to The Veterinary Record, tortoises that receive sufficient calcium in their diet have the highest growth rate and better overall health.

how long does it take for a tortoise to grow?

Early Skeletal Damage

Stunted growth in tortoises often arises due to injuries in their formative years.

Young tortoises are more vulnerable to skeletal or shell damage. When this happens, the normal growth of tortoises can stall, causing them to remain small.

So, if a tortoise had a fall at a young age, this may explain why it doesn’t grow to the same size as others. This can be true even if the tortoise appears to have fully recovered from its injury.

Internal Parasites

According to Parasitology Research, internal parasites are common in tortoise species.

The most prevalent are ascarids, such as roundworms and pinworms; protozoans, like cryptosporidium; flukes, and amoeba. So, it’s important to check for worms in tortoises’ feces.

While not all parasites are dangerous for tortoises (some are entirely natural), most attack the gastrointestinal organs of their host, depriving them of the nutrients they need to grow.


Stress can cause a tortoise to stop growing properly, so its enclosure must be peaceful and relaxed. So, avoid loud noises, bright lights, sudden activity, and other animals (including pet cats and dogs).

Tortoises are loners, so they’re unlikely to appreciate another tortoise’s company, especially one from a different species or a second male. Tortoises only usually come together to breed.

Also, ensure that the tortoise has plenty to do, as a tortoise will become stressed without enrichment. Add climbing structures, foraging toys, digging materials, and hides to the tortoise’s enclosure.

Sub-optimal Temperature And Humidity

Tortoises require a warm, humid enclosure to be healthy and grow. If the ambient temperature is too cold or hot, it can lead to stunted growth.

Optimal temperatures for tortoises are species-specific, but 70-85°F (21-29°C) is usually optimal. Also, the humidity level should be 50-80%.

Tortoises become inactive if the temperature is too low, slowing their growth. Also, tortoises become stressed and dehydrated if the temperature gets too hot, resulting in stunted growth.

How To Tell If A Tortoise Is Not Growing

Identifying stunted growth in a tortoise isn’t always easy, especially with small species. That’s further compounded by the fact that most tortoises grow at such a slow rate.

There are two ways to track the growth of a tortoise. Measuring and weighing the tortoise every few months will determine whether it’s steadily increasing in size.

Alternatively, you can trace an outline of the tortoise on a piece of paper every few months. Then, you can compare the drawn outlines to determine if they’re getting bigger.

How Long Does It Take For A Tortoise To Grow?

The growth rate of individual tortoises varies based on their species, diet, and living environment. A tortoise’s shell will grow with them.

Usually, captive tortoises grow faster than wild varieties due to the over-consumption of high-protein foods. Protein usually accounts for under 15% of a wild tortoise’s diet.

Although tortoises should consume some protein, feeding them protein-rich foods regularly or in large amounts isn’t advisable.

Excessive protein leads to rapid shell growth, but the shell composition is less dense. Unfortunately, this can lead to irreversible shell conditions, such as shell pyramiding.

How To Make A Tortoise Grow Faster

Most slow or stunted growth cases occur due to unsuitable living conditions and dietary issues.

Unless the tortoise has a genetic condition that prevents it from growing properly, there are ways to promote faster growth. These include the following:

Spacious Enclosure

For tortoises to grow, they need enough space to roam freely, dig and burrow, and climb surfaces.

Housing a tortoise in a large enclosure with lots of room allows it to remain active and improves its gut motility, assisting with the absorption of nutrients.

Basking Area

Tortoises require UVB light to facilitate healthy bone and shell growth.

Although wild tortoises usually bask in the sun during the day to meet their UVB light needs, they must be provided with artificial UV-emitting bulbs in captivity.

Nutrient-Rich Diet

Providing a nutrient-rich diet is among the most important things you can do to ensure the tortoise grows healthily and to its optimal size.

Tortoises need a diet rich in calcium, phosphorus, magnesium, zinc, and Vitamins A and D. The best foods for tortoises include non-toxic plants and vegetables like:

  • Dandelions.
  • Clovers.
  • Geranium.
  • Clover.
  • Aloe vera.
  • Collard greens.
  • Carrots.
  • Broccoli.
  • Brussel sprouts.

Unless you have a fruit-eating species, like the red-footed or Hermann’s tortoise, fruit consumption should be limited to prevent digestive issues that inhibit nutrient absorption.

Gastrointestinal Parasites

Tortoises are prone to internal parasites, such as worms, mites, and ticks.

Parasites cause damage to the gastrointestinal organs, depriving tortoises of the nutrients they must grow and thrive. They can adversely affect tortoises’ growth rate and health.