Do Turtles Need Calcium?

Turtles are wonderful creatures, but since they’re reptiles, they tend to have a few crucial differences when compared to us mammals.

This can sometimes make them a little difficult to care for since you’ll need to learn the things that they can and can’t consume.

There are also some vitamins and minerals that are essential for turtles.

Today, we’re going to explore the importance of calcium in a turtle’s diet.

We’re going to look at whether or not turtles need calcium and the role that calcium plays in a turtle’s system.

We’ll also go over the best way to give you turtle calcium, and we’ll even look at one of the best calcium supplements for turtles on the market.

Do Turtles Need Calcium?Calcium is one of the essential parts of any turtle’s diet, and it’s one of the pillars that they need to grow big and strong. The other two vitamins that are absolutely necessary in a turtle’s diet are phosphorous and Vitamin D3. If you provide a turtle with calcium and these two other vitamins, they’ll live a healthy life.

Turtles require phosphorous so they can develop stronger bones and shells, though vitamin D3 serves a different purpose for them.

Ironically enough, the only reason why turtles need vitamin D3 in the first place is so that they can absorb calcium more easily. In the end, it all comes back to calcium.

What Does Calcium Do for Turtles?

Since calcium is recommended to make up about 2% of a healthy turtle’s diet, it begs the question of why turtles need calcium so badly.

Calcium is used to form the harder structures in our bodies, and the same can be said for turtles. Calcium is also crucial for healthy muscles.

The most notable characteristic of a turtle, the shell, is also formed out of a large amount of calcium, showing you just how crucial this vitamin is for these animals.

Along with maintaining their shells, turtles also need calcium to ensure that their bones remain as healthy as possible.

Calcium also helps turtles combat several diseases, which we’ll explore later on when we look at what will happen to a turtle if it’s deprived of calcium.

Keep in mind that phosphorous isn’t the only thing that turtles require to properly process the calcium that’s included in their diets.

Turtles also need calcium to maintain healthy muscular systems, as they will be unable to contract their muscles if they don’t have enough of it.

One of the main factors that helps turtles with the absorption of calcium is UV light, which is why you typically need to install a UV lightbulb in your turtle’s enclosure to ensure that it’s as healthy as possible.

How Much Calcium Do Turtles Need?

The amount of calcium that you need to feed your turtle every day depends on its size, so you’ll want to make sure that you determine the proportion of your turtle’s diet that is calcium instead of the raw amount.

There are a few ways to introduce calcium into your turtle’s diet that we’ll be looking at later on.

Whether you decide to give your turtle calcium supplements or provide them with a diet that’s rich in calcium is up to you.

If you decide to go the route of supplements,

then it will be easier to determine how much you need to be giving your turtle because it will likely be outlined on the bottle’s instructions.

Most calcium supplements will let you know how much calcium you need to be feeding your turtle per unit of body weight, ensuring that the formula works for turtles of all sizes. I

f you’d rather come up with how much calcium you need to be feeding your turtle yourself, you’ll have to refer to the study that we mentioned earlier.

The study was conducted with red-eared sliders in particular, but the numbers will probably be similar across all turtle species because of the sheer level of biological similarity between them.

It’s recommended that about 2% of your turtle’s total nutrition per day be made up of calcium.

How Do I Give My Turtle Calcium?

While most of the nutrients required by turtles are included in their diets already, calcium is a clear omission that may often go unnoticed until your turtle starts to exhibit signs of calcium deficiency.

By then, your turtle may have suffered a negative impact to its health, so it’s essential that you know how to make sure that your reptile friend gets all of the calcium it needs.

Most turtle owners go either one of two ways.

They will either serve their turtle a diet that is naturally high in calcium or they’ll just decide to feed them calcium supplements to make up for the lack of it in their pet’s diet.

Either of these options has its pros and cons.

For example, picky turtles may not be willing to eat the food that you give them that’s high in calcium, but the same may be the case with calcium supplements.

If your turtle is suspicious of the supplements you’re offering it, then you’ll have to find a way to disguise them and trick your turtle into eating them.

Opting for calcium supplements may also be more expensive in the long run, as they’ll often be pricier than the basic foods you can feed your turtle to ensure that it gets all the calcium it needs.

Food Containing Calcium That Can Be Given to Turtles

There are a few different foods that are high in calcium that you can provide your turtle, but some of them won’t make for good dietary staples.

One of the best calcium-rich foods you can feed turtles is kale, which will have no negative side effects if fed to turtles on a daily basis.

You can read more about it here -> Can Turtles Eat Kale?

Other foods that are high in calcium include crayfish, but they shouldn’t be fed to turtles daily. Save them as a treat that will help boost your turtle’s calcium levels. Earthworms are another good option, but they contain plenty of fat that can be bad for your turtle in large enough concentrations.

Here is a video on feeding calcium to turtles.

Can Turtles Have too Much Calcium?

If you’re feeding your turtle a diet that’s rich in calcium, you may be worried that you’re feeding your reptile friend too much of the nutrient.

There are certainly some nutrients that should not be fed to turtles excessively, and you should try to avoid doing so with calcium from a perspective of waste mitigation, but nothing will likely happen to your turtle.

This is because calcium is water-soluble, which means that any excess calcium in your turtle’s system won’t build up and become harmful. Instead, the calcium will find its way into your turtle’s urine and will leave its body just as easily as it entered it.

The amount of calcium that a turtle can use is dependent on how much of it its system needs.

However, to process large amounts of calcium, your turtle will also need a sufficient amount of Vitamin D3.

This means that the max amount of calcium that your turtle’s body can handle will depend on how well its D3 levels are doing.

If your turtle only has enough D3 to process a little bit of calcium, the rest of it will be lost in the animal’s urine.


How Do Turtles Get Calcium in the Wild?

You would figure that turtles in the wild would be more deprived of calcium than those living as our pets because of the ease of providing them with calcium in a controlled environment, but that’s not the case.

In fact,

turtles in the wild tend to have better calcium levels than those that are kept in captivity.

It makes sense when you think about it.

If all wild turtles were calcium deficient, then the species would likely have already died off due to disease in the wild.

The simple fact is that turtles can typically find a way to ensure that they get enough calcium in their diets when left to their own devices.

While turtles may seem like herbivores because of their penchant for eating greens, that’s just because the food is typically available in large amounts without much work on the turtle’s part.

However, if a turtle sees a source of protein or calcium that’s another animal, it will take its opportunity.

Some of the most common sources of calcium for wild turtles include crayfish and shrimp, as their shells provide turtles with a huge boost of calcium.

Another source of calcium includes small fish species, as their bones or cartilage also tend to contain plenty of calcium.

Cuttlebone and Turtles

Cuttlebone is a bone that is found in all cuttlefish species, typically used to control buoyancy in these fish species.

Among a wide range of other applications, cuttlebones are an excellent way to supplement your turtle’s diet with calcium, as a cuttlebone is loaded full of the necessary vitamin.

Along with feeding turtles, cuttlebone is also used as a dietary supplement for several other captive animal species, including birds, crabs, reptiles, and snails.

If you want to feed your turtle cuttlebone, it will essentially be a calcium supplement, and it has a few advantages.

One of the best parts of feeding your turtle cuttlebone is that your turtle can decide how much of the bone it wants to eat.

As long as your turtle doesn’t have any dietary conditions, this means that it will be able to regulate its calcium intake on its own, but there are also a few potential downsides to it.

The first con to cuttlebone is that it has to be prepared before being given to your turtle to ensure that it doesn’t choke on it.

Another issue is that the cuttlebone can eventually disintegrate in your turtle’s enclosure, saturating the water with particles.

Calcium Deficiency in Turtles

So what happens when a turtle doesn’t get enough calcium?

That depends on the age of your turtle.

If turtles are starved of calcium at a younger age, then they may run into an issue where their shell doesn’t develop properly.

In most cases, the shell will end up being uneven, and this can’t be corrected later in life.

One of the most common issues in turtles that haven’t received enough calcium is a metabolic condition.

This condition is known as metabolic bone disease and it will result in brittle or weak structures that depend on calcium in the body, including a turtle’s shell and bones.

In the worst cases, metabolic bone disease can result in turtles experiencing tremors and they may even suffer sudden fractures of their bones due to the structure wearing away.

Due to the effects on the muscular structure of a turtle caused by calcium deprivation, turtles may also experience noticeable weakness.

If a turtle is pregnant and suffering from calcium deficiency, then she may not even be able to lay her eggs properly because of her inability to contract her muscles.

This condition is known as being egg-bound.

Best Calcium Supplement for Turtles – Repti Calcium


  • Contains precipitated calcium carbonate
  • Phosphorous-free
  • The formula contains vitamin D3 to improve your turtle’s calcium absorption
  • No oyster shells used in its production
  • High surface area per gram because of the unique shape


Zoo Med’s Repti Calcium is not just for reptiles, as the name would suggest. While this supplement can be used with reptiles, it’s also designed for reptiles like turtles. This supplement is designed with a high level of bioavailability in mind, ensuring that it’s a lot easier for your turtle to absorb.

This solution also contains vitamin D3 to make it easier for your turtle to absorb the calcium that’s contained in it. Since Repti Calcium isn’t made out of oyster shells, it also doesn’t have any impurities in it that can potentially harm your turtle.

We were also impressed by the design of the supplements themselves, as they feature a large surface area that will make it easier for your turtle’s system to process the calcium that they contain.

Also read

Do Turtles Need Sunlight




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