Tortoises enjoy eating brightly-colored foods with interesting smells. Unfortunately, with so many plants, fruits, and vegetables available, poisoning and toxicity are ever-present risks.
Tortoises shouldn’t eat flowers like poinsettias, gardenias, holly, hyacinth, and hydrangeas.
Off-limits vegetables include eggplant, broccoli, chili pepper, alliums, wild mushrooms, and unripe tomatoes. Citrus fruit, avocado, and gooseberry are bad for tortoises.
Also, avoid feeding tortoises prickly lettuce and wild lettuce, as some tortoise species will find that different foods make them unwell.
Most tortoises, including horsefields, are herbivorous and shouldn’t be fed meat, while rainforest tortoises are meat-eaters.
What Foods Can Tortoises Not Eat?
Some foods should never be fed to any tortoise, regardless of their species.
Toxic food for tortoises contains compounds such as:
- Cyanogenic substances: The body can turn these into cyanide.
- Alkaloids: This compound is responsible for the toxicity of nightshade plants.
- Glycosides: Some glycosides can affect the heart and the nervous system.
- Oxalates (oxalic acid): Oxalates can prevent the body from absorbing calcium.
To ensure your tortoise’s mealtimes are safe, we’ll provide a “what can tortoises not eat?” list so that you’ll know which fruits, vegetables, plants, and flowers to avoid.
What Plants Can Tortoises Not Eat?
Tortoises love to eat flowers, choosing which ones to eat based on their bright coloring and smell. However, many flowers are toxic, upsetting your tortoise’s digestion.
The following plants/flowers should be avoided:
- Lily of the valley
- Spider mum
The toxicity of the poinsettia plant comes from the cardiac glycosides found in its sap, and these compounds affect how the cardiac muscle contract.
When the sap touches the skin, it may cause rashes or irritate the eyes.
When ingested, your tortoise may develop the following symptoms:
- Stomach aches
All parts of the poinsettia should be considered unsafe for tortoises.
The toxic compounds in gardenia include geniposide and gardenoside, which cause gastrointestinal issues in cats, dogs, and horses.
Gardenia poisoning in animals usually manifests as:
All parts of the plant, including the flower, contain these toxins.
Holly is toxic to tortoises due to the different glycosides and saponins.
According to the Western Journal of Emergency Medicine, saponin can destroy red blood cells and affect the permeability of the small intestine.
When consumed, holly can cause the following adverse reactions:
- Abdominal cramps
What Vegetables Can Tortoises Not Eat?
Not all vegetables are safe for your tortoise to eat.
Although this list contains vegetables that are packed with vitamins and minerals, they can have a damaging effect on your tortoise’s health.
The eggplant (aubergine) is a member of the nightshade family.
All parts of the eggplant contain different solanaceous compounds, which are the source of toxins found in nightshade plants.
Most of these compounds are concentrated in the green parts of the eggplant (leaves, stems, and tops). The eggplant is okay for tortoises in small amounts, but too much can lead to poisoning.
The symptoms of eggplant ingestion include:
- Upset stomach
For this reason, it’s best to be cautious and feed your tortoise other vegetables.
Broccoli isn’t outright toxic, but it contains compounds that can irritate a tortoise’s stomach.
Specifically, these are goitrogens, which impact the thyroid and affect how the body absorbs iodine. Broccoli can lead to liver and kidney damage, especially in large amounts.
Thyroid hormones are responsible for a tortoise’s growth, metabolism, and the creation and maintenance of skin cells. If too much goitrogen is ingested, it can make your tortoise shed prematurely, stunt its growth, and cause kidney and bladder stones.
Chili peppers aren’t poisonous to tortoises but can irritate the mouth, eyes, and skin.
This is due to the compound capsaicin, which gives the plant its spice. It can be found in all parts of a chili pepper but is most concentrated in the seeds and the inner lining of the pepper’s walls.
Chili is avoided by most animals, except birds, which lack the taste receptors to detect capsaicin.
Alliums consist of onions, garlic, shallots, leeks, and chives. This group of plants is believed to be toxic to tortoises, causing digestive issues and more severe problems when eaten in large amounts.
Allium toxins are called n-propyl disulfide, which can destroy red blood cells. The toxicity remains potent when alliums are raw, cooked, dried, or powdered.
Symptoms of allium toxicity include:
- Gastrointestinal upset
Unless you have been trained to identify wild mushrooms, never feed them to your tortoises, as mushrooms can look very similar from one species to another.
For example, the destroying angel, one of the most toxic mushrooms, is nearly impossible to distinguish from button mushrooms to the untrained eye.
Tomatoes are from the nightshade family and contain many of the same compounds.
The toxicity is derived from solanine (a natural insecticide) and tomatine. The latter has fungicidal, antimicrobial, and insecticidal properties.
Ripe tomatoes have fewer of these compounds but should still be avoided. Tomatoes contain too much phosphorus and have minimal calcium and fiber.
Other parts of the plant, like tomato tops, stems, and leaves, are also toxic to tortoises.
What Lettuce Can Tortoises Not Eat?
There are two main types of lettuce to avoid:
- Prickly lettuce
- Wild lettuce
Prickly lettuce (Lactuca serriola) contains large amounts of lactucarium in its sap. Lactucarium is used as a sedative and narcotic, causing cardiac paralysis in large amounts.
Also, wild lettuce contains significant amounts of lactucarium.
Iceberg lettuce contains very few nutrients and is mostly composed of water. Besides staving off dehydration, Iceberg lettuce won’t make your tortoise any healthier.
What Fruit Can Tortoises Not Eat?
A tortoise’s diet should consist of 5-10% fruit, but not all types are safe.
Avoid feeding your tortoise the following fruits:
Citrus fruit is widely regarded as toxic to tortoises. While official studies are limited, there’s reason to believe that citrus could be harmful.
Citrus is poisonous to many domesticated animals due to essential oils, such as limonene and linalool.
Psoralens, present in all citrus fruit, are toxic to pets. According to the Archives of Dermatology, psoralens lead to long-term health risks in humans.
The symptoms of citrus poisoning in animals include:
Avocado is poisonous to many animals, so it’s wise to avoid feeding it to tortoises. The compound persin causes digestive issues., but the symptoms of persin toxicity differ from one animal species to another.
It has been shown to cause mastitis in mammals and even decrease milk production in cows and goats. In rabbits, it causes arrhythmia, edema in the salivary glands, and eventual death.
Studies haven’t explored its effects on tortoises, but all parts of the avocado plant contain persin and may be toxic to reptiles, so they should be avoided.
The young, fresh leaves of gooseberry contain small amounts of hydrogen cyanide.
Gooseberry, in large amounts, may cause respiratory issues and eventual death. A small nibble won’t kill your tortoise, but you should never feed your tortoise gooseberries.
Additionally, unripe gooseberry fruit should be avoided. Like other nightshade plants, toxic compounds tend to lessen in the fruit once ripened.