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Can Turtles Eat Onions? Why You Shouldn’t Feed It!

Can Turtles Eat Onions? Why You Shouldn’t Feed It!

Our curiosity around what turtles can eat will never subside. Call it my generosity or inquisitiveness, I want my turtle to enjoy a wide range of meals once in a while. 

With lots of choices on the card, one cannot be sure which food is safe for our pets and which isn’t. 

In this episode, I will discuss one such option, onion. Is it safe for turtles?

Let’s find out.

Can Turtles Eat Onions?

Onions are highly acidic for a turtle’s sensitive digestive system. Therefore, you should never feed them onions. Whether raw or cooked, you shouldn’t serve it to your pet reptile. 

This article will explain why onions are considered the “forbidden vegetable” for turtles. Also, by the end of this article, you will be able to know which other veggies your pet should avoid. So, stick till the end!

Nutrition Content In Onion

100 grams of onions have the following:

  • Protein: 1.1 g
  • Carbohydrates: 9.34 g
  • Sugar: 4.24 g
  • Niacin (B3): 0.116 mg
  • Pantothenic Acid(B5): 0.123 mg
  • Folate: 19 mcg
  • Vitamin C (L-ascorbic acid): 7.4 mg
  • Calcium: 23 mg
  • Phosphorus: 29 mg
  • Magnesium: 10 mg
  • Potassium: 146 mg
  • Iron: 0.21 mg

As you can see from the content above, there are a plethora of acidic elements in an onion. To name a few, they are niacin, pantothenic acid, folate, L-ascorbic acid, and phosphorus.

Though all these nutrients are beneficial for us, they bode ill news for turtles. 

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Why Shouldn’t You Feed Onions To Turtles?

You must have learned by now to avoid giving onions to your little pets. Some ill effects onions have on turtles are heartburn, metabolic bone disease, anemia, and digestive disorders.

Causes Heartburn

Onions are acidic in nature. This leads to toxic overload in their system and causes a burning sensation in their mouth and throat. 

In severe cases, it results in heartburn, causing discomfort in breathing. 

Causes MBD (Metabolic Bone Disorder) 

Your turtle’s system needs to neutralize the acidic reflux at the expense of alkaline minerals like calcium to counter heartburn. 

If the turtle’s body overcompensates, it is likely to suffer from calcium deficiency, which results in MBD. 

Some symptoms of MBD are:

  • Swelling of legs
  • Arching of spine
  • Bumps along the spine, legs, and tail
  • Tremors
  • Brittle bones

Has Improper Calcium To Phosphorus Ratio

The ideal ratio of calcium and phosphorus should be 2:1. However, that is not the case with onions. 

From the above nutrient content list, we can see that the phosphorus level is higher than calcium. This means that consuming onion will result in more deposition of phosphorus.

When this ratio isn’t met, the phosphorus interferes with the system and binds calcium, resulting in calcium deficiency. This further leads to metabolic bone disease.

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Can Turtles Eat Raspberries?

Can Turtles Eat Flies? Feed These Insects Instead!

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Can Turtles Eat Snails? (What Kind And How Many Per Day?)

Causes Anemia

Yes, it may come as a surprise to you, but turtles do suffer from anemia. This is because of the two culprits that are found in onions. They are sulfoxides and sulfides. They can incite a disease called Heinz body anemia.

When affected, the red blood cells in your turtle’s body will deplete faster than they are produced, resulting in the turtle’s death. 

Causes Digestive Disorders

The same previously mentioned toxic acids will cause indigestion. A turtle’s digestive system isn’t adept enough to digest these acids. 

As a result, your turtle will throw up onions soon after consuming them.

Can You Feed Cooked Onion To Turtles?

When it comes to onions, you should keep them away from your turtle’s reach. The effects of toxic elements in onion are so evident that it will not matter whether you cook, boil or deep-fry them before serving. 

To put it bluntly, serving onions in any form is doing fatal harm to your turtles.

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What To Do If Your Turtle Accidentally Ate Onions?

Accidents can never be predicted. And if that is what happened in your turtle’s case, you should immediately watch how your turtle reacts after eating onions. 

First, if your turtle shows erratic behavior, do not panic. Call a vet and explain the situation. If the vet deems it an emergency case, heed their advice. 

Sometimes, your turtle could have eaten only a small piece. In that case, you might not have to worry. 

But, if you notice any signs that are away from the norms, you should take it to the vet immediately without further ado. 

How To Prevent Such Accidents In The Future?

You should always take precautions to minimize the risk of feeding turtles unsafe food. 

Here’s how you can do it:

Single-handed feeding will drastically minimize putting your turtle in harm’s way. 

Make a staple diet plan. This way, you won’t have to experiment with new food on the spot.

Other Fruits And Veggies That Are Harmful To Turtles

Just in case you thought onions were the only veggies to contain toxic elements, it isn’t so. 

Remember that any veggies that grow from the bulb, like onion, garlic, and leek, are harmful to turtles.

Here are some other fruits and veggies which you should avoid feeding your turtles:


Rhubarbs have a high amount of oxalates which binds calcium in your turtle’s system, preventing mineral absorption. 


You should by no means feed avocado to your turtles. It contains persin, a fungicidal toxin, which can cause organ failures. 

If you want to know why you should avoid giving turtles avocado, here’s an article to learn more: Can Turtles Eat Avocado? Poisonous Fruit Ever?


Though you might have read that turtles should be fed leafy veggies, you shouldn’t overdo it, especially spinach.

Spinach has high oxalate content, a calcium-binding composition that prevents mineral absorption. 

And this can lead to MBD (Metabolic Bone Disease). 

To know more, read Can Turtles Eat Spinach? Spinach Have Oxalates!

Final Words On Can Turtles Eat Onions

The contents of onions and other veggies that grow from bulbs have always been considered to bear antioxidants that fight cancer cells.

Well, that is the benefit of onions to us. 

But when it comes to turtles, it is quite the opposite. The same acids that help humans are fatal for our little friends. 

No matter how much you like your turtles to eat the same food as you do, it isn’t advised to do so. 

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Can Turtles Eat Grass? What About Flowers, Succulents, And Herbs?

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Can Turtles Eat Eggs? What About Frog Eggs?

Can Turtles Eat Cherries? Read These 3 Risk Factors First