Can Crested Geckos Eat Bananas and How to Feed Them?


Crested geckos eat fruit and insects in the wild. However, in captivity fruit should only be given in moderation as you can do a lot wrong as a beginner. Crested geckos need a good calcium-to-phosphorus ratio and sadly most fruits have a bad ratio. But what about bananas?

Can crested geckos eat bananas? Crested geckos can eat bananas but only as an occasional treat. Bananas have a (very) bad calcium-to-phosphorus ratio but do have a low oxalic acid level. Bananas are a more popular treat for crested geckos. It’s best to make a fruit mash of bananas with other more suitable fruit.

When you’re new to crested geckos, you want to give a commercial crested gecko diet supplemented with insects. It’s recommended to give fruit, including bananas, only as a treat to your crested gecko. For more experienced owners that know what they’re doing fruit can play a more important part in the diet.

In this article, you’ll learn a little bit about the nutritional value of bananas and why they’re mostly suitable as a treat for your crested gecko and not as the foundation of a crested gecko diet. Finally, you’ll learn how to feed them to your crestie.

Nutritional Value of Bananas

Bananas are edible fruit and you can find bananas almost anywhere in the world. They are a more tropical fruit and are known for their high amount of potassium. Bananas can be eaten fresh, processed, or baked.

The following nutritional data comes from FoodData Central:

NameAmountUnit
Water74.91g
Energy89kcal
Protein1.09g
Total lipid (fat)0.33g
Carbohydrate, by difference22.84g
Fiber, total dietary2.6g
Sugars, total including NLEA12.23g
Calcium, Ca5mg
Iron, Fe0.26mg
Magnesium, Mg27mg
Phosphorus, P22mg
Potassium, K358mg
Sodium, Na1mg
Zinc, Zn0.15mg
Copper, Cu0.078mg
Selenium, Se1µg
Vitamin C, total ascorbic acid8.7mg
Thiamin0.031mg
Riboflavin0.073mg
Niacin0.665mg
Vitamin B-60.367mg
Folate, total20µg
Folic acid0µg
Folate, food20µg
Folate, DFE20µg
Choline, total9.8mg
Vitamin B-120µg
Vitamin B-12, added0µg
Vitamin A, RAE3µg
Retinol0µg
Carotene, beta26µg
Carotene, alpha25µg
Cryptoxanthin, beta0µg
Lycopene0µg
Lutein + zeaxanthin22µg
Vitamin E (alpha-tocopherol)0.1mg
Vitamin E, added0mg
Vitamin D (D2 + D3)0µg
Vitamin K (phylloquinone)0.5µg
Fatty acids, total saturated0.112g

Are Bananas Good or Bad for Crested Geckos?

To determine whether bananas are good or bad for crested geckos we need to take a look at two important nutrient levels:

  • the calcium-to-phosphorus ratio (Ca:P ratio)
  • the level of oxalic acid

Ca:P ratio of bananas

Introduction to Ca:P ratio

Crested geckos need calcium to stay healthy and to prevent the development of a specific disease called metabolic bone disease. Gravid females, hatchlings and juveniles have a special need for calcium because they need the calcium to grow and to form eggshells (in the case of gravid females).

Calcium and phosphorus have a special relationship. When the calcium levels raise the phosphate levels are lowered and when the phosphate levels rise, the calcium levels drop. This means that, for crested geckos, foods should contain a lower amount of phosphorus than calcium.

A widely used tool to determine if a food is suitable for crested geckos, the calcium to phosphorus rate is used. The Ca:P ratio can be described as a percentage but is more often described in terms of [number]:1 or 1:[number], where the 1 is the mineral that’s the lowest of the two. To calculate the calcium to phosphorus ratio this way you’ll need to bring back the lowest number to 1. So, the ratio is calculated by dividing the largest number by the lowest number.

Research has shown that good calcium to phosphorus ratio (Ca:P) is between 1:1 and 2:1. For crested geckos, it’s recommended to have a calcium to phosphorus ratio of 2:1 or better.

Calculating the Ca:P ratio

NutrientAmountCalculations
Calcium5 mg5/5=1
Phosphorus22 mg22/5=4.4
Ca:P ratio1:4.4

So, the Ca:P ratio of bananas is 1:4.4, which is considered a (very) bad ratio. This doesn’t mean that bananas are bad, but you should be aware that they aren’t that beneficial for crested geckos as for example papayas.

Oxalic acid in bananas

Introduction to oxalic acids

Oxalic acid is a compound that’s found naturally in living organisms such as vegetables and fruits. It can be sometimes tasted in food when the amount of oxalic acid is very high. Textbook examples of plants that have a level of high oxalic acid are rhubarbs, star fruit, and spinach.

Oxalic acid is associated with the inhibition of calcium and the formation of kidney stones in humans. Crested geckos also need to avoid eating food that has a high level of oxalic acid. The compound will bound with minerals such as magnesium and calcium and form oxalates (tiny rectangular crystals).

Since calcium is essential for crested geckos, it’s recommended to stay away from foods that have a medium level of oxalic acid and to avoid foods with a high level of oxalic acid altogether.

Oxalic acid level of bananas

Bananas have a low level of oxalic acid and won’t cause any problems, at least in this aspect.

Bananas are good as a treat

A crested gecko diet needs to have a good Ca:P and should be low in oxalic acid. Bananas won’t give your crested gecko the necessary nutrients but can occasionally be given as a treat.

Feeding Bananas to Crested Geckos

How many times to feed bananas?

There are some gecko owners that give their own balanced diet consisting of insects and fruits to their crested geckos. However, there exist enough good commercial diets that offer all the nutrients needed.

If you’re a new crested gecko owner and don’t have experience with balancing the diet of a crested gecko, your crested gecko will benefit the most from a meal replacement powder that has a high nutritional value and add bananas or even better a fruit mash as a treat once or twice a month.

How many bananas can you feed?

If you make a mashed fruit puree you can fill a shallow dish with the same amount as a normal meal replacement powder. If you give fruit as a treat you can give a small piece of a banana and mash it up.

How to feed bananas to crested geckos?

Crested geckos can’t bite hard so you need to be careful that the food you give can be eaten. Fruits are often mashed in a puree to make them edible. Bananas are already quite soft and don’t need a lot of biting power. Still, when you feed bananas to your crested gecko you can still mash it. You can also soften the banana by exposing the slices to air for a bit before giving them. This will soften them up.

Another way crested geckos can eat bananas is by giving (almost) rotten bananas. In nature, crested geckos will eat rotten fruit that has fallen on the ground because it’s much softer.

A step-by-step guide to feeding bananas

  1. Wash the bananas

    The peel of bananas can contain a lot of bacteria and pesticides. You’ll need to wash the banana to make sure that your crested gecko doesn’t ingest bad bacteria or pesticides.

  2. Peel and slice the banana

    Peel off the hard skin of the banana and slice it in small pieces. Since crested geckos will only eat a small slice of the banana, you can eat the other slices yourself.

  3. Mash it up in a fruit puree (optional)

    You can feed the slice of banana to your crested gecko or mash it in a fruit puree with yogurt and other fruits like papayas.

  4. Fill a feeding cup with the banana slice or the fruit puree

    You don’t want to overfeed your crested gecko. So, only give the same amount of food as a meal replacement powder. Your crestie will lick and bite in the slice or puree and will need little to no biting power.

Want to Learn More?

If you want to learn more about crested geckos as pets, please read the following articles.

If you’re interested in getting crested geckos as pets you should also definitely read our article about baby and juvenile crested gecko care or (adult) crested gecko care.


Kevin N.

Kevin is the owner of My Crested Gecko. He wrote this blog for many years and has been a geckos enthusiast his entire life, but only became an official "geckophile" five years ago when he acquired one as a pet! Kevin knows how to care for hamsters, guinea pigs, rabbits, and degus in addition to crested geckos which are more than happy with him every day!

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