Can Turtles Eat Onions

Can Turtles Eat Onions? (Is Onion Good for Turtles)

If you have a pet turtle, chances are you’ve wanted to share your food with your pet. It’s only natural, as most feline and canine owners share their food with their pets. However, sharing some food items with your turtle, such as onions may not be a good idea.

So, can turtles eat onions? The answer is no – turtles can’t eat onions. Onions are extremely toxic for turtles. They have highly acidic elements, which don’t bode well with turtles’ sensitive stomachs. Raw, cooked, or dissolved onions are not recommended for turtles in any condition.

In this article, we’re going to talk about why onions are so bad for turtles. And what you should do in case your turtle consumes onions. Keep reading if you’d like to learn more.

Can You Feed Onions To Your Pet Turtle?


The short answer is – absolutely not. Since it’s a vegetable, a lot of people might automatically assume that it’s okay to feed onions to turtles. In actuality, onions are considered the “forbidden vegetable” for turtles. You shouldn’t give your pet turtle onions in their diet.

Can You Feed Onions To Your Pet Turtle

Turtles have a sensitive digestive system that cannot process complex acidic elements and sugar contents. Having known that, let’s take a look at the basic elements found in 100 grams of onions.

  • Carbohydrates: 9.34 g
  • Sugar: 4.24 g
  • Protein: 1.1 g
  • Calcium: 23 mg
  • Phosphorus: 29 mg
  • Vitamin C (L-ascorbic acid): 7.4 mg
  • Pantothenic Acid (B5): 0.123 mg
  • Folate: 19 mcg
  • Potassium: 146 mg
  • Magnesium: 10 mg
  • Iron: 0.21 mg

This content list clarifies why you can’t and shouldn’t feed onions to your pet turtle. Even though onions are not high on carbs, they contain sugar – which turtles cannot digest. 

Then we can see that onions have almost the same amounts of calcium and phosphorus in them, creating a 1:1 ratio – which is not an ideal ratio. Taking these minerals in the wrong ratio will have devastating effects on your pet reptile. 

If we take another look, we’ll see that onions have a variety of acids in them (L-ascorbic acid, Pantothenic acid, Folate, Potassium) – all of which are available in adequate amounts. These acids are particularly harmful to the health of turtles. This is why turtle owners are discouraged from giving their turtles acidic food and vegetables. 

Onions also contain an element called ‘thiosulfate’. This compound causes turtles to lose their red blood cells. This can be absolutely life-threatening for a turtle.

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All in all, onions are not recommended as a food option for turtles.

Do Turtles Like Onions?

Turtles cannot digest onions easily. If you feed them onions, they’ll usually throw up and even become sick. So turtles don’t like onions. 

Turtles Like Onions

Health Risks for Turtles Eating Onions

Onions contain a lot of antioxidants and nutritional components. However these elements are only good for humans. In fact, they pose quite a lot of health risks for turtles. Let’s take a look at some of them – 

Turtles Eating Onions

Digestive Disorders

Onions contain sugar, pantothenic acid, and folate, all of which are very toxic for turtles. Since turtles have a sensitive stomach that cannot digest acids and sugar contents, these elements cause turtles digestive problems, making them vomit. 


Onions are rich in acidic elements, such as L-ascorbic acid, pantothenic acid, folate, and potassium. Since the acidic elements are so potent, consuming onions has a drastic effect on turtles. Even a little bit of onion will cause turtles to have an acidic overdose, giving them heartburn and a burning sensation in their mouth, throat, and tongue. This can even lead to a breath shortage and, in extreme cases, death. 

Calcium Deficiency

Turtles need a 2:1 calcium to phosphorus ratio in their diet. A turtle’s body must contain double the amount of calcium than the phosphorus it is consuming. 

If the phosphorus level is higher than that, the phosphorus starts to interfere with the body and bind the calcium. This results in a calcium deficiency in turtles. Calcium deficiency can result in Metabolic Bone Disease – weakened, deformed, and broken shells, as well as brittle bones

Turtles Eating Onions

As we can see from the content list, onions have an incorrect ratio of calcium and phosphorus. It has more phosphorus than it ideally should, which can result in calcium deficiency in the turtle’s body. Causing them all sorts of health problems in the long run. 


There are three very specific elements found in onions – they are sulfoxides, sulfides, and thiosulfate. These can trigger disease in your turtle, which is known as Heinz body anemia. These acids basically deplete the turtle’s body of red blood cells faster than their production rate, causing them anemia and eventually death. 

How Much Onions Should Turtles Eat?

Turtles usually don’t prefer onions over other vegetables since they cannot digest them properly. So you shouldn’t give them onions, not even a little bit.

How Much Onions Should Turtles Eat

Can You Feed Onions to Baby Turtles?

Absolutely not. You should not feed onions to baby turtles under any circumstances. Onions are deadly enough for mature turtles. Feeding onions to premature turtles can lead to their untimely death since their stomachs are underdeveloped. 

Baby Turtles

Video of a Turtle Eating Onions

Turtles don’t know what they should or shouldn’t eat. It is up to the pet owners to monitor what their turtles are eating. In this video, you can see a turtle munching on a piece of onion. 

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Russian tortoise likes onion

Frequently Asked Questions (FAQs)

1. Can Box Turtles Eat Onions?

Although box turtles are omnivores and can eat a lot of things, onions can bring the same damage it does to other turtles. In short, they cannot and shouldn’t be fed onions. 

2. Can Red Eared Slider Turtles Eat Onions?

Onions are extremely toxic to red eared slider turtles because they have an extra sensitive stomach. If taken in small amounts, it can cause diarrhea. If taken in larger quantities, it can lead to the turtle’s death.

3. Can Painted Turtles Eat Onions?

Painted turtles have the same physiology as any other turtle, so if you have a painted turtle as a pet, it is highly discouraged to feed them onions. Painted turtles are semi-aquatic, so they’re not used to eating onions anyway. They may not object to it if you give it to them, but the repercussions are deadly.


Onions and other bulb-grown vegetables are great for us humans but equally bad for our shell-bound friend. If you have a turtle as a pet, be a responsible parent and don’t feed it onions. There are plenty of other vegetables that are actually good for your turtle. In this article, we’ve tried to shed light on everything about turtles and onions. We hope this was helpful.

If you want to know if turtles eat spiders or kale? Read our articles about it to learn more.

Can Turtles Eat Onions

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