Crested geckos are one of the easiest reptiles to keep for novice enthusiasts because there are several frugivorous gecko foods available in pet shops and online. The list of acceptable commercial diets has grown, as interest in providing variety while maintaining the ease of a powdered meal replacement product is a hot topic. While it seems like everyone and their brother have their own crested gecko recipe in the works, it’s important to understand some basics in nutrition before deciding on a primary product or home-brewed recipe.
Whole foods are the only source of nutrition in the wild: live, whole prey and unprocessed vegetable matter. Therefore, it might seem strange to offer dry, kibbled or semi-moist foods. Wild foods offer the variety that is required in nature for animals to survive. However, in captivity we are severely limited in the choice of food items due to climate, availability, and the fear of herbicides, pesticides, toxic metals and other contaminants in the environment that affect wild caught bugs and field harvested plants. To make up for nutritional deficiencies, we must opt for other solutions. Domestic produce from the supermarket rarely provides enough protein, calcium and fiber, vitamins or trace minerals to support every life stage. You need to supplement the diet, whether that means sprinkling a powder onto a fruit blend or feeder insect, or mixing a complete packaged diet with water to make a smoothie. By understanding the ingredients in popular pet foods, including those for crested geckos, we can choose the most appropriate diet. You may find that the “unnatural” powdered foods are based on whole food nutrition.
“Although some prepared foods have been available for only a limited time, the overall nutritional quality of commercially prepared foods is rapidly improving as manufacturers consider new scientific information when they prepare their formulations.” – Stahl and Donoghue, 2010 “Nutrition of Reptiles”, Small animal clinical nutrition, fifth edition
The most important step in choosing an appropriate commercially prepared crested gecko food is to Read the Label! The order of ingredients is important, as they are usually listed by quantity, with the bulk ingredients at the front and the trace elements at the end. Many pet food manufacturers neglect this and at times you’ll see labels quietly changed to reflect the true ratios. Let’s walk through some of the necessary elements.
Macronutrients: Protein, Fat & Carbohydrates
Each reptile species has varying needs, whether carnivore, omnivore, insectivore, frugivore or herbivore. Little is known about the specific nutritional requirements for crested geckos, but they are classified as omnivores. Anecdotal reports conflict on how much of their diet is comprised of fruit, pollen, nectar or insects, but these are all possible foods to a wild crested gecko. Because of this, it’s best to opt for variety to ensure your gecko gets the proper nutrition and stimulation from their captive diet.
Susan Donoghue & Julie Langenberg, in Douglas Mader’s Reptile Medicine and Surgery (pg 151), report generalized reptile nutrition statistics as follows:
- Carnivores should consume 25-60% protein, 30-60% fat and <10% carbohydrate
- Omnivores should consume 15-40% protein, 5-40% fat and 20-75% carbohydrate
- Herbivores should consume 15-35% protein, <10% fat, and 55-75% carbohydrate
Proteins are important chemical compounds of amino acids. These amino acids get broken apart from the protein chain so they can then be used for various functions within the body. Essential amino acids are required from foods, while non-essential ones can be bio-synthesized within the body (but also can be extracted from food). Insects, on a Dry Matter Basis, range from around 40-76% protein. However, each insect species varies and there is also variation among individual insects depending on life stage and diet. It is assumed that most (non-toxic, parasite-free) insects should be appropriate for omnivores that consume invertebrate prey.
It is worth noting that insects can lack essential amino acids. Notably, in chickens fed an insect-meal diet, these limiting amino acids included arginine and methionine. Good sources of arginine are dairy products, meat, wheat germ and many nuts and seeds, including pumpkin and sesame. Good sources of methionine are eggs, meat, sesame seeds, oats and other cereal grains.
Plant proteins are also variable in their essential amino acid content. Cereals are low in lysine while legumes are low on methionine. So providing a good variety of both insects, animal products and plant proteins can help ensure your pet is getting the proper “building blocks”, as protein is often dubbed.
Growth rates generally correlate to protein intake, assuming temperatures are adequate for metabolization. This is why adding insects to the diet, even when feeding a commercial product, seems to result in faster growth. As omnivores, a crested gecko’s diet should contain 15%-40% protein. Most commercial gecko foods are 20-30%.
Fats are another important element to reptile diets. Fatty acids are a nutritional requirement, assisting in the absorption of Vitamins A, D, E & K, acting as an energy storehouse, cushioning internal organs and maintaining body temperature. Good sources of fats in commercial diet should contain linoleic acid and linolenic acid (the omega oils), which are lacking in roach species used for live food. Good sources include flax, safflower, chia, hemp and soy oils. A variety of insects can provide different levels of fatty acids, so include crickets, roaches, waxworms, silkworms & soldier fly larva. As omnivores, a crested gecko’s diet should range between 5-40% fat. This is a wide range, and we don’t know exactly what crested geckos need. Too much fat can cause obesity!
Carbohydrates are another piece of the nutritional pie. For crested geckos, this is provided not only directly from the fruit and nectars they eat, but also the gut contents of feeder insects. Their main carbohydrates should be relatively high in sugars and low in fiber, the composition of most fruits. The omnivorous reptile should consume 20-75% carbohydrate.
Dietary Minerals & Vitamins
Calcium is probably the most talked about nutrient in reptile diets because it is the most often deficient in the captive diet. What isn’t as well known is the necessity of Vitamin D3 in the calcium absorption process. This vitamin, technically a hormone, is a unlike most other nutrients as it can be synthesized by the body if given adequate exposure to UVB light. UVB can come from special lighting or from unfiltered sunlight. Dietary D3 can be supplemented for insectivores, as insects do not contain much, if any, D3. As nocturnal animals, it is uncertain how efficient crested geckos are at utilizing UVB for D3 synthesis, so it has been included in most commercial brands.
Many people dump on excessive amounts of calcium powder into fruit mixes and onto feeder insects, which comes with its own set of problems. Calcium requirements for mammals and birds is set at 1% of the diet, with Phosphorus .5%, and Vitamin D3 at 200 to 1000 IU/kg. Maximum tolerances (the upper limits in the diet) are 2.5% calcium, 1.6% phosphorus and 5000 IU/kg for D3.
Interactions between vitamins (A, D & E in a ratio of 100:10:1) and calcium and phosphorus, complicate the nutritional spectrum in terms of trace minerals. “Common problems are deficiencies of zinc, copper, or iodine due to excessive calcium supplementation, and conditional vitamin E deficiencies due to polyunsaturated fatty acids.” (Mader 165)
Common Additions to Commercial Diets
Obviously, the goal of any gecko food should be to combine healthy ingredients with delicious ingredients. If your gecko won’t eat it, what’s the point of it being healthy? So you may find some interesting items on the labels of commercial diets.
- Dried Honey: this makes it taste sweet and can act as a preservative
- Bee Pollen: can act as an appetite stimulant and provides nutrients
- Weird Green Stuff: AKA spirulina, kelp & algae which add iodine & trace minerals
- Herbs & Spices: Paprika, turmeric and other spices contain carotenoids that boost coloration and play a part in maintaining good health.
If your brand of gecko diet doesn’t have any of the above, it doesn’t mean it’s not healthy. The addition of some of these ingredients may seem like a gimmick, but many do provide actual health benefits beyond just hype.
Homemade Diets vs Commercial Food
Unfortunately, the foods we think of as natural become less nutritious or otherwise unsuitable as a mainstay. Feeding only muscle meat to a carnivore may seem a simple way to care for their nutritional needs, but it doesn’t provide the wealth of minerals and vitamins found in the bones, organs and viscera of a whole animal. Many dog, cat and ferret enthusiasts have found benefits in feeding whole prey to their pets.
For frugivorous reptiles like crested geckos, we are tempted to throw some fruit in a blender and call it “gecko food”. However, such a blend may be a nice treat every once in a while, but it’s not a balanced diet. By denaturing the fruit (often missing the peel, seeds and insects often present in aged fruit which they feed on naturally), we are concentrating the sugar and calories down into something very nutritionally dense, which could cause obesity and imbalance of other nutrients over time.
You can attempt to make a crested gecko diet yourself, if you feel you are up to the challenge. You don’t have to rely on a commercial product. Many keepers have the knowledge and experience to make healthy fruit blends at home. Just be sure you pick the right fruits and your supplements are fresh, as vitamins erode after about 6 months. Provide a balanced diet to your feeder insects and be sure to dust them! Many keepers feed a supplemented fruit mix 2-3 nights a week and bugs twice a week with good results.
Gecko Food Summary
Adding fresh fruit to the diet a few times a month, along with feeding gutloaded, dusted bugs is a way of adding variety while still relying on a well-balanced commercial diet. Just make sure to read the labels and check that it’s actually providing a complete diet. Forget about brand loyalty, it’s all about what’s good for your geckos! It may take some time to settle on a primary food. But with all the choices available, you should be able to choose one that your geckos will readily eat that provides the nutrition they need.
Douglas R Mader, Reptile Medicine & Surgery.
Merck Veterinary Manual: Reptile Nutrition
Stahl, S, Donoghue, S. 2010. Nutrition of Reptiles. In Small animal clinical nutrition, fifth edition: 1237-1254.