Choosing a turtle or tortoise: adult size, decades, and the pre-purchase check

Quick answer

A red-eared slider. The most commonly bought pet turtle in the world, and the one most commonly surrendered, released or found dead in a tank that was never big enough.

The decision that determines whether a turtle lives well is made before you own it, in a shop, in about ten minutes.

Two facts do most of the work. The commonly sold species reach a size and an age that almost nobody is told about: a female red-eared slider grows to roughly dinner-plate proportions and can live for decades, and an African spurred tortoise sold as a hatchling the size of a biscuit becomes an animal measured in tens of kilograms. And a great many shop turtles are already ill in ways that are visible if you know where to look.

• Ask for the Latin name, the adult size and the adult enclosure requirement before you ask the price.
• Swollen, closed eyelids and bubbles at the nose are the two commonest visible illnesses in shop turtles, and both mean walk away.
• The rule of thumb keepers use for aquatic turtles is roughly forty litres of water for every two and a half centimetres of shell length, which is a very large tank for an adult.
• Check the law where you live. Several commonly sold species are restricted, and some sales are outright prohibited.
• Adopting an adult from a rescue gets you a hardy animal at its final size with a known history.

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Never release an unwanted turtle or tortoise into a pond, river, lake or the countryside.

Released sliders have established breeding populations across Europe, Asia, Australia and the Americas, where they compete with native species for basking sites and food and introduce disease. It is why several species are now legally restricted, and in many countries release is a criminal offence.

If you can no longer keep the animal, the routes are a chelonian rescue, a specialist keeper, or your vet. Never the outside world, and never a local pond because it looks suitable.
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Decide in 60 seconds

What you are actually committing to

Decades.

Red-eared sliders commonly live twenty to thirty years or more in good conditions. Mediterranean tortoises such as Hermann's and spur-thighed are routinely quoted at fifty to a hundred years and beyond, which means the animal will outlive many of the people buying it.

That has a practical consequence people find uncomfortable: a tortoise needs to be written into a will, with a named person and a plan. It is not a morbid detail, it is the difference between a settled old animal and one that ends up in a rescue at forty.

Adult size, not shop size.

This is where most of the damage is done. A hatchling slider fits in a palm. A mature female reaches roughly the size of a dinner plate. An African spurred tortoise, sold across the world as a hatchling, grows into an animal measured in tens of kilograms that digs burrows large enough to undermine walls and needs year-round outdoor space in a warm climate.

Ask the adult size in centimetres and the adult enclosure in square metres. If the answer is vague, that is your answer.

Space and water.

The rule of thumb aquarists and keepers use for aquatic turtles is around forty litres of water for every two and a half centimetres of shell length. Apply that to an adult female slider and you have a tank most homes cannot accommodate, before you add the basking platform, the lighting and the floor loading of that much water.

Tortoises need floor area rather than volume, and much more of it than the wooden vivaria sold for them provide. A tortoise table or a large outdoor enclosure is the realistic setup.

Filtration, for aquatic species.

Turtles are messy in a way fish are not. They tear food apart, they defecate heavily, and uneaten protein rots. The usual advice is to run a filter rated for two or three times the tank's actual water volume, and to change water frequently regardless. Poor water quality is behind most shell disease, skin infections and eye problems in pet turtles.

Heat and ultraviolet light, permanently.

A basking lamp, a source of ultraviolet B, a water heater for aquatic species, and thermostats for all of it. These are not optional extras. Without ultraviolet B a chelonian cannot use dietary calcium properly, and metabolic bone disease follows.

Time, every day.

Preparing and measuring food, and changing water. This is the routine that has to keep happening for thirty years, long after the novelty has gone.

Food prepared and portioned, water changed, temperatures checked, basking area kept dry, and hands washed properly every time. It is not a heavy commitment on any one day. It is a heavy commitment across three decades.

Veterinary care, from a specialist.

Chelonian medicine is a specialism. Not every practice sees them, imaging and surgery in a shelled animal is technically demanding, and treatment for common problems such as aural abscesses and egg binding involves surgery. Find the vet before you buy, not during the first emergency.

The species that are mis-sold

Red-eared sliders, yellow-bellied sliders and cooters.

Large, long-lived, hardy, and invasive where released. Hardy is why they survive the poor conditions they are usually kept in, and why so many are surrendered as adults rather than dying young.

African spurred tortoise.

Sold as a hatchling everywhere, and one of the least appropriate pets for a temperate climate or an ordinary home. It is a grassland grazer that becomes enormous, digs extensively, and needs heated outdoor space.

Common and alligator snapping turtles.

Large, powerful, capable of serious injury, and restricted or prohibited in many jurisdictions.

Softshell turtles.

Delicate skin, specific substrate needs, prone to abrasion and infection, and unsuitable for a first setup.

Wild-caught box turtles and other wild-caught chelonians.

Wild-caught animals adapt poorly to captivity, carry parasite burdens, and are protected in many regions. Ask directly whether the animal is captive bred and press for a straight answer.

Any hatchling sold in a small plastic bowl.

That style of sale tells you what advice came with it. In the United States the sale of turtles under four inches has been prohibited for decades, precisely because small turtles ended up in the hands of small children and caused salmonella infections.

The law, which differs sharply by region

This is one of the few pet purchases where the legal position can change what you may keep, and it varies more than people expect.

The European Union lists the red-eared slider and several related sliders as invasive alien species of Union concern. Sale and breeding are prohibited, and keeping is restricted to existing animals under conditions that prevent escape and reproduction.

The United States prohibits the sale of turtles with a shell under four inches, a rule introduced on public health grounds. Individual states add their own restrictions on native species and on snapping turtles.

CITES covers many tortoise species. Buying one without the correct paperwork can leave you unable to sell, move or legally keep the animal, and can be an offence. Ask for the documentation and keep it.

Local rules on native species collection, on releasing, and on licensing vary widely. Check before you commit, not afterwards.

The pre-purchase health check

You can do all of this by looking, in a couple of minutes.

Eyes.

Open, clear, and the same on both sides. Puffy, swollen or closed eyelids are the classic presentation of vitamin A deficiency, which is extremely common in turtles fed poorly. It is treatable, but it tells you how the whole batch has been kept, and the same diet has been affecting the kidneys and respiratory lining at the same time.

Nose and breathing.

No bubbles, no discharge, no crust around the nostrils. Watch the animal breathe. Clicking, wheezing, open-mouth breathing, stretching the neck upward, or an aquatic turtle swimming tilted to one side all point at respiratory infection. On a shared filtration system that is a whole-system problem.

Ears.

Look at the side of the head behind the eye. It should be flat. A firm, domed swelling on one or both sides is an aural abscess, which is common in turtles kept in poor water and needs surgery.

Shell, from above.

Smooth growth, no raised pyramid-shaped scutes, no soft or dented areas, no white chalky patches, no red or pink discoloration under the scutes, and no smell. Lifting scutes with material underneath means shell rot.

Some softness in the plastron of a very young hatchling is normal. Softness in a juvenile or adult is metabolic bone disease.

Plastron, underneath.

Ask to see it. Flat, clean, no ulcers, no reddening, no pitting.

Limbs, head and tail.

All four limbs moving normally and symmetrically. No swelling at the joints, which suggests gout or infection. Claws and toes present. The tail intact.

Body condition.

The limbs and neck should fill the shell openings reasonably. A turtle that withdraws with a great deal of room to spare, or that has loose skin folds at the neck, is thin, dehydrated, or both.

Behaviour.

Alert, responsive, withdrawing when approached, swimming level, and using the basking platform. A turtle floating with one side higher, or unable to submerge, has a serious problem.

The feeding test.

Ask for the animal to be fed while you watch. Healthy chelonians of the commonly sold species are enthusiastic feeders. Refusal is the single most informative thing you can observe.

The system, not just the animal.

Look at the water in every tank on the rack, whether the tanks share filtration, whether there is a dry basking area under a working lamp, and whether the ultraviolet fitting looks like it has been changed this decade. One sick turtle on a shared system disqualifies the system.

The questions worth asking

Ask what the animal has actually been fed. A turtle raised on dried shrimp and nothing else arrives with a deficiency you will spend months correcting.

"What is the Latin name?"

Common names are unreliable and several very different animals share them. The Latin name lets you look up adult size, lifespan, temperature range, diet and legal status before you decide.

"Is it captive bred or wild caught, and where from?"

Captive bred is what you want. A vague answer is an answer.

"What size does it reach, and what enclosure does an adult need?"

Ask in centimetres and in square metres or litres.

"What has it been eating, and can I watch it eat?"

Both halves matter. A turtle raised on a single item arrives deficient, and one that will not eat in the shop rarely starts at home.

"What temperatures has it been kept at, in the water and on the basking site?"

It tells you what the animal is adapted to and what to set up.

"Is there paperwork?"

For CITES-listed tortoises this is not optional, and it should come with the animal.

Before you bring one home

The alternative most people should take

Rescues are full of adult sliders and sulcatas, surrendered by owners who were told none of the above.

An adult chelonian from a rescue is at its final size, so there is no surprise. It is past the fragile juvenile stage. Its history and diet are usually documented. Its temperament is known. And it frequently comes with the enclosure, because the previous owner had already bought one.

If you want a smaller commitment, ask about the genuinely smaller species. Musk turtles and mud turtles stay small enough for a realistic home tank, and among tortoises the Mediterranean species are far more manageable than a spurred tortoise.

Match the animal to your climate as well as your space. A Mediterranean tortoise in a cool wet climate needs substantial indoor infrastructure and a considered decision about brumation each year. A spurred tortoise in that climate is not a workable proposition at all.

What never to do

Do not buy a chelonian on the same trip that you buy the tank. Set the system up and run it first.

Do not buy a turtle from a tank where any animal has swollen eyes, nasal bubbles or shell damage.

Do not accept a common name as an identification.

Do not buy a hatchling because it is small now.

Do not keep a chelonian without ultraviolet B and a basking site, whatever the shop says.

Do not buy a wild-caught animal.

Do not skip the legal check, particularly in the European Union and for CITES-listed tortoises.

Do not house two turtles together on the assumption they will be company. Competition over basking space is a common and injurious problem.

Do not release, rehome informally, or hand an animal to someone who has not been told what it becomes.

When to get help

Register with a chelonian-competent veterinary practice as soon as you buy, and take a new animal for a health check within the first few weeks rather than waiting for a problem. Ask for a faecal parasite examination, which is worth doing on any new arrival and essential on anything that might be wild caught.

Go quickly, in the first weeks or at any time afterwards, for swollen or closed eyelids, bubbles or discharge at the nose, clicking or open-mouth breathing, swimming tilted or an inability to submerge, a firm swelling behind the eye, a soft or smelly shell, refusal to eat, or straining.

Bring these to the appointment: the species name, where the animal came from and when, what it has eaten since you got it and what it was fed before, your water and basking temperatures and what you measured them with, the ultraviolet bulb type, its distance and the date it was fitted, water test results for an aquatic species, the animal's weight and shell length, and your shop photographs.

Expect the husbandry questions to come first, because in chelonian medicine the enclosure is a substantial part of the clinical picture. Expect the vet to want to see the animal periodically rather than only when something is wrong, since shell and bone changes develop over months and are far easier to correct early.

Ask what this species should weigh relative to its shell length, and how to measure both. A number you can track at home turns a decades-long commitment into something you can actually monitor.