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How Fast Do Red-Eared Sliders Grow? You Won’t Believe!

How Fast Do Red-Eared Sliders Grow? You Won’t Believe!

As a pet parent, it is essential to know how fast and big a turtle can grow. If you have the correct information, you will have the proper estimation of the tank size you have to get for your turtle. 

Today, we will be diving into the growth chart of a red-eared slider turtle. We will discuss their growth pace, the maximum size they can reach, and how to help them reach their full growth potential. 

How Fast Do Red-Eared Sliders Grow?

Red-eared sliders grow the fastest in their first year. They can grow over 3 inches by their first birthday. From the second year onwards, they will grow at the rate of 1 inch per year.

Females tend to grow for a longer period than males. 

Red-eared sliders will reach their maximum size at the age of 7. 

At the end of year 7, males reach about 8 to 10 inches long, whereas females can reach 10 to 12 inches. 

Red-eared sliders can get quite big to house in an aquarium when they reach adulthood. They are one of the largest pond turtle species we keep as pets. 

The aforesaid red-eared slider’s growth rate reveals that it can grow quickly and require a large tank to match its size.

Here’s a growth chart for red-eared slider turtles:

1 – 3 months1 to 2 inches long
1st year3 to 4 inches long
2nd year 4 to 5 inches long
3 year5 to 6 inches long
4 year6 to 7 inches long
5 year7 to 8 inches long
6 year8 to 9 inches long
7 year9 to 10 inches long

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How Big Do Red-Eared Sliders Get?

Adult Turtle With A Juvenile On Its Back

Full-grown female red-eared sliders can reach up to 12 inches in shell length. Males, on the contrary, are smaller and will reach up to 10 inches in shell length. This growth is expected to plateau at the age of 7.

Several factors play an important role in the growth rate of red-eared slider turtles. Let me explain them in detail. 

Water Parameters And Red-Eared Sliders Growth

It is a no-brainer that optimum water parameters should be met while raising red-eared sliders. Here’s what ideal water parameters for a turtle tank looks like:


Water temperature should be maintained between 75 to 80 degrees Fahrenheit. On the dry side, it can be anywhere from 84 to 94 degrees Fahrenheit. 

Although these are the suitable water parameters, red-eared sliders can still survive below or above the preferred temperature – but it’s not recommended.

pH Value

A pH range of 6.0 to 8.0 is preferred for red-eared sliders. 

Ammonia, Nitrite, And Nitrate Levels

These all should be kept at 0, as they can seriously hamper a red-eared slider’s health and halt their growth. 

Check time and again to see if there’s a spike in any of these elements.

I use this water testing kit from API since liquid-based kits are far more accurate than strips. This kit measures five important water parameters: pH, high pH, ammonia, nitrite, and nitrate. 

You also need to check the water for the presence of chlorine. For example, if you use tap water for your red-eared slider tank, you should dechlorinate and only use it. 

Here’s a quick link to a water conditioner from API that absolutely gets the job done:

Diet And Red-Eared Slider Turtles Growth

Diet has a direct impact on a turtle’s growth rate. An all-round diet ensures healthy growth in turtles. Baby turtles require more calcium and protein to aid their development. 

So, you need to feed them food that is rich in these two nutrients.

Calcium For Turtles Growth

All turtles need calcium. It helps them to build better muscles and strengthens bones and shells. Lack of calcium can cause MBD, Metabolic Bone Disease

Turtles suffering from MBD have weak skeletal structures. Their carapace and plastron become fragile and can break even with minor impact. 

Along with the brittle skeletal system and shell, lack of calcium also weakens muscle contraction. Furthermore, if the calcium level drops too low, the turtle can get a cardiac arrest. So, you know how vital a calcium-rich diet is for turtles. 

According to one study – Calcium Requirements of Red-eared Slider Turtles – by the Journal of Zoo Animal Medicine, red-eared sliders need at least 2% of calcium from their overall diet. 

So, you should prioritize including calcium-rich food in your turtle’s diet.

Food that is high in calcium and can be fed to turtles are:

  • Whole freshwater fish
  • Insects and invertebrates
  • Commercial pellets
  • Calcium blocks

Whole Freshwater Fish

Freshwater fish are an excellent source of calcium. Minnows and golden shiners can fulfill the calcium demand of turtles. 

Unlike adults, baby turtles do not prefer eating veggies and plants. They need to consume a meaty diet to supplement their growth.

So, whole freshwater fish can be fed as a source of calcium to your red-eared sliders, especially babies.

If you are interested to read up on how to catch minnows using an awesome hack, check this article: How To Catch Mud Minnows? Use This Awesome Hack

Insects And Invertebrates

Insects and invertebrates are other excellent sources of calcium. Turtles love them. Crustaceans and crayfish should be fed with their exoskeleton. These outer shells are high in calcium. 

Commercial Pellets

Commercial pellets can also fulfill the calcium demand of turtles. Most options available to us are specially formulated with turtles’ health needs in mind.

However, they shouldn’t be fed as complete substitutes for whole fishes, insects, invertebrates, and other meaty diets. 

Calcium Blocks

If you think that your turtle isn’t getting enough calcium from its diet, you can use calcium blocks to reinforce this nutrient.

These slow-releasing calcium blocks help condition water and provide calcium to your turtle. Turtles do not get harmed even if they consume it. 

Here’s a link to slow-release calcium blocks by Zoo Med if you are interested:

Protein For Growth

Scientific journals have revealed that there is an immense role of protein in red-eared slider turtles’ growth. Protein helps to elevate thermal conditions, resulting in the rapid growth we see in a baby turtle’s first year. 

Foods that are rich in protein are mealworms, earthworms, crickets, and feeder fish. Baby turtles at the growing stage will depend more on a meat-based diet rather than plants.

Also, their metabolism is higher than adult turtles. So, baby turtles are always hungry. 

However, protein should be fed in moderation. 

Excess feeding of protein-rich diets can cause pyramiding, the raising of scutes at an abnormal rate. 

The shells will have heavy deposits of keratin, resulting in increased shell diameter.

You can easily identify pyramiding. The abnormality causes difficulty in the movement for turtles. 

So, do not overfeed your turtles even if they ask for more food. 

Vitamins For Growth

If you provide a diverse range of food to your turtles, they will presumably get much of the needed vitamins and nutrients from the diet itself. 

However, two vitamins are more important to turtles than others. They are:

  • Vitamin A
  • Vitamin D

Vitamin A For Red-Eared Sliders

Vitamin A helps in developing healthy skin, mucous membranes, and ducts within organs in turtles. 

Lack of vitamin A can cause: 

  • Problems related to vision
  • Occurrence of hypovitaminosis A
  • Respiratory infection
  • Abscesses in ears and hearing problems
  • Squamous metaplasia (thickening of the duct lining in kidneys and pancreas)

The lack of vitamin A is seen especially among turtles older than six months. Before six months of age, the baby turtle’s need for vitamin A is supplemented by the egg yolk.

Gradually the yolk reserve will deplete after a few months of nourishment. 

As the source of vitamin A depletes, turtles will need further supplements to replenish the vitamin in their body. 

If the baby turtles lack vitamin A, it directly hampers their growth.

Symptoms of vitamin A deficiencies in turtles are:

  • Swollen eyelids
  • Loss of appetite
  • Mouth infection
  • Respiratory infection

You now know how important vitamin A is for a turtle’s growth. Without it, turtles will suffer from respiratory infections, along with severe health complications. 

Their disinterest in eating will halt their growth. Malnutrition is to be expected in turtles, who lack vitamin A.

So, to prevent this, you can give your red-eared sliders foods that are rich in vitamin A.

Some of them are:

  • Sweet potatoes
  • Carrots
  • Yellow or winter squash
  • Leafy green veggies (ones that are less in oxalates, e.g., Kale)
  • Whole fish or codfish liver oil

If you do not want to go through the hassle of peeling and cooking these veggies, you can always go for commercial supplements as an alternative.

But do not rule out feeding leafy veggies even when giving vitamin A supplements.

Here’s a vitamin A supplement from Rep-Cal that I give my turtles regularly. Let me tell you why I chose this vitamin supplement for my sliders, in fact, for all my turtles. 

Just like how lack of vitamin A has severe effects on turtles, the same can happen when they intake an immoderate amount of vitamin A. 

So, this formula contains beta carotene, antioxidants, carotenoid, and pigments that help filter potential toxicity resulting from excessive amounts of vitamin A in a turtle’s system. 

Now I do not have to worry about the right amount of vitamin A concentration in their food.

Vitamin D

Unlike vitamin A, turtles do not require supplements for vitamin D. They obtain vitamin D (Vitamin D3) from their environment. 

The exposure of UV light onto the turtle’s skin triggers the pigment cell, producing vitamin D3. 

So, natural or artificial light, UV rays are necessary for turtles to produce vitamin D3. Without this vitamin, a turtle’s body will not be able to metabolize the calcium present in its body.

And when there’s a deficiency of vitamin D3 in turtles, they develop the metabolic bone disease. 

To fulfill the vitamin D demands, you can place your red-eared sliders in spots where they can bask under direct sunlight. You can keep them for about an hour, twice a week.

Do not go overboard by putting them in hot areas for more than the required time. This can backfire by burning your turtle’s skin and cause dehydration. 

During winter, the UV light, along with the heat bulb, will suffice a turtle’s need for UV rays. Make sure you get a UV bulb that emits both UVA and UVB rays. 

I use this UV light for my turtle tank that produces both UVA and UVB rays. What I like about this lamp is that it imitates sunshine, perfect for my turtles.

Tank Requirements For Red-Eared Slider Turtles

It will be tricky to accommodate red-eared sliders in a tank. They are one of the largest among semi-aquatic turtle species. So, their rapid growth is one of the reasons why you should get a bigger tank in the first place.

Baby red-eared sliders can be housed in a 30-gallon tank. 

One rule of thumb is 10 gallons per inch. It means that if your turtle is 2 inches, you will need a 20-gallon tank. 

So, as a starter, get a 30-gallon tank to house baby red-eared sliders.

For juvenile turtles, it will be better to get a tank depending on its size. Juveniles grow at a slower rate after their first year. They will grow 1 inch per year. 

So, a 60-gallon tank will hold your juveniles for a couple of years. 

Adult red-eared slider turtles can be anywhere from 8 to 12 inches. Females grow larger than males, so you might even need a bigger tank. 

You will need at least a 100-gallon tank to house these adults. 

So, I recommend getting a stock tank for your adult red-eared sliders. These stock tanks do not cost as much as the glass ones and can be easily filled with 200 to 300 gallons of water. 

Here’s a cool video of a 300-gallon stock tank for turtles: 

Why Turtles In The Wild Grow Faster And Bigger Than Those In Captivity?

Wild turtles consume all kinds of wild plants, vegetables, and insects. Although they do not have the luxury of eating crayfish or other fast-moving fish, their diet in the wild fulfills every nutritional requirement.

So, this heterogeneous diet they consume helps them grow faster and bigger than captive turtles. 

Captive turtles, on the other hand, have a repetitive staple diet. They also get far less exercise than their wild cousins. So, they grow at a slower rate.

Final Words On How Fast Do Red-Eared Sliders Grow

Baby red-eared sliders grow prolifically. They can grow up to 3 inches in their first year. After that, they grow around an inch per year. 

Various factors play a crucial role in determining a red-eared slider’s growth. Habitat and diet are two such variables. A well-rounded diet with abundant amounts of calcium and protein is necessary for growing turtles. 

Their growth rate also depends upon the size of the tank, water parameters, and so forth. So, you must maintain suitable parameters when keeping red-eared sliders.

Relevant Readings:

Where To Release Baby Snapping Turtles? Is It Even Legal?

What To Do If A Turtle Lays Eggs In Your Yard? Will They Hatch?

How To Trim Turtle Nails? 3 Items You Will Require