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A C Highfield

Aquatic turtles are very popular pets - but unfortunately, many die as a result of non-existent or incorrect care information. This article summarizes the basic facts you need to know to maintain these species in good health.

Feeding aquatic turtles

Most terrapins and freshwater aquatic turtles are omnivorous rather than exclusively carnivorous, consuming both animal prey and plant material in the wild. This pattern should be encouraged in captivity. Some are definitely more carnivorous than others, but even my voracious Common Snapping turtle (Chelydra serpentina) has been known to take plants in preference to its more usual meaty fare on occasions. In all cases, however, it is certainly not adequate to feed only on commercial turtle flakes which are often of very poor nutritional value and severely lacking in dietary fibre, vitamins and minerals. Nor should whitebait or similar fish form the staple diet, as these are excessively rich in oil and can result in steatitis or fatty infiltration of the liver. Diets containing excessive quantities of fish can also result in induced vitamin-B deficiencies due to the presence in fish of an enzyme called thiaminase, which interferes with the take up of B-group vitamins.
The main thing to avoid with diets for any captive turtle is over-reliance upon one single item; this is a very easy mistake to make, but a balanced and varied diet is infinitely superior. Provide as wide a range of the following food items as you possibly can. It is also worth noting that the sex of certain turtles affects their preferred diet; for example, female Common Map Turtles (
Graptemys geographica) have a much wider mouth than males and therefore take larger prey. Whereas the females of this species feed predominantly upon large snails and other molluscs, the males prey mainly upon aquatic insects and smaller snails.

Suggested aquatic turtle diet

  • Plant leaf material
  • Raw (whole) fish
  • Rehydrated dried cat, dog or trout pellets
  • Quality prepared food such as 'Reptomin'
  • Earthworms
  • Snails and molluscs

Where food is to be rehydrated, as with the dried cat or dog pellets available in pet stores, rehydrate using water plus a soluble vitamin additive. This is a highly successful way of ensuring that your turtle will obtain all of the essential vitamins and trace elements it requires.

For more detailed feeding advice see the link at the bottom of this article to our 'Aquatic Turtle Feeding Guide'.

Finally on the topic of feeding, it is definitely the case in my experience that over-rather than under-feeding tends to be the main problem in many captive situations; in the long term this can prove just as damaging as underfeeding. Not only must the quality of the diet be maintained within safe limits, but the quantity too. This applies equally to land tortoises and aquatic turtles; in the latter case if you overfeed you will not only get fatty, obese and lethargic turtles but you will also very quickly experience serious tank hygiene problems - and an almost certain outcome of that will be a dramatic increase in the incidence of infectious disease. In most cases, feeding 3 times per week will be quite adequate. Daily feeding is hardly ever required with aquatic turtles.

Mainly aquatic temperate freshwater turtles

This group includes the most popular of all turtles to be kept as a pet, the North American Red-eared Slider (Trachemys scripta elegans). It also includes a number of less frequently seen turtles from the same region such as Map turtles (Graptemys sp.), Common or Alligator Snapping Turtles (Chelydra serpentina and Macroclemys temmincki), Soft-shell turtles (Apalone/Trionyx sp.) and both Musk and Mud turtles (Sternotherus sp. and Kinosternon sp.)

Softshell turtle

Clearly, within such a range of species the fine detail of habitat preference differs considerably from one to another, but nonetheless all do share a basic tolerance to a cold winter and hot summer seasonal cycle. Whilst most of the temperate climate aquatic turtles sold in pet shops are of North American origin, a few European species are seen from time to time including the European Pond Terrapin (Emys orbicularis) and the Spanish Terrapin (Mauremys leprosa). Like their American cousins these turtles are found in rivers, ponds and streams and all are more or less entirely carnivorous although some vegetable material is consumed from time to time. In many species the young are much more carnivorous than the adults; a fact to bear in mind when feeding in captivity. Green leaf plant food should always be available however. The female lays her eggs out of the water in a nest dug into a suitable sunny riverbank in late spring or early summer. In the wild, such turtles hibernate in the thick mud on the bottom of rivers or ponds, or in excavations made in riverbanks. In captivity, it is usually safer to overwinter them.

Map Turtle

North American aquatic turtles will become relatively torpid as temperatures fall below 15oC, and enter hibernation below 10oC, and European turtles respond in the same way. To overwinter, maintain temperatures above 20oC at all times.

Tropical & temperate aquatic turtles

Most of these turtles are well suited to a vivarium environment, although in some cases outdoor accommodation can be utilised during the warm summer months. Because these are all relatively small species, it is possible to base the vivarium around standard tropical fish tanks - however, only large ones are usually suitable. The minimum I would normally consider satisfactory for a fully grown adult pair of Red-eared sliders for example is 2m (6 feet) long x 500mm (24 inches) wide. This should be 50/50 to 75/25 land and water in most cases. Other housing options that offer superior qualities to glass tanks are available, however. See the links at the end of this article. In particular, the surface-mount pond concept is vastly superior.


All indoor terrapin tanks or ponds will require some form of artificial lighting. Ordinary tungsten light bulbs are not suitable by themselves but they can provide a useful source of basking heat and their low colour temperature (orange-yellow) also appears to encourage basking. We recommend the use of 100W or 160W reflector spot lamps for basking purposes. For the main light source the best system by far are UV-B heat lamps. The benefits of this type of lighting are two-fold; the colour temperature of the light is 5,500 degrees K which is close to natural daylight thus encouraging natural activity and behavioural patterns and in addition these lamps also emit Ultra-Violet radiation which is important as it contributes to the natural production of Vitamin D3 (essential to healthy bone development). UV-B is blocked by glass, so even if a tank is placed in a brightly lit window position this is not by itself adequate. A UV-B emitting lamp will provide the missing component indoors. In practice, if a multi-vitamin and mineral supplement such as Vionate, Rep-Cal or Nutrobal is used regularly it is highly unlikely that any D3 deficiency will occur. Even so, the overall benefits of a Full Spectrum Lighting system are enormous and I would regard it as an essential component of any exclusively indoor maintenance system, not merely on account of their UV-B output, but rather because they so closely approximate the colour temperature of natural daylight and therefore do tend to reduce stress and encourage normal behaviour. Where non-FSL lighting is used, I have noted an increased tendency to lethargy and inactivity. Fluorescent UV-B tubes may also be used, but in this instance, a separate basking lamp will be required. Please consult the special 'Lighting' article linked at the bottom of this page for extra information on lighting options.


General warmth can be provided by a combination of undertank heater-thermostats and overhead basking lamps (60W should be adequate in most cases for the latter). If a UV-Heat lamp is used, however, this will provide both UV-B and heat for basking.The air humidity should be medium-high, but certainly not saturated; make sure that there is good ventilation at all times.
For most North American turtles, which are the kinds most often kept as pets, the water temperature should be maintained in the range 23 C to 29 C. Excessively high temperatures (over 32 C) or prolonged periods at too low a temperature (less than 20 C) can be dangerous.
A word on normal fishtank type heater-thermostats. These are obviously electrical devices and it is well known that electricity and water is not a good combination. Many heater-thermostats are also encased in glass; this is fine in the tranquil surroundings of a tropical fish tank but an aggressive terrapin or rampaging Snapping turtle can soon cause untold damage. In my experience their casing can all too easily be fractured allowing the water in the tank to become `live' - this is a potentially lethal situation for owner and turtle alike. A further hazard is that the heater may be used as a plaything and end up out of the water; should this occur it will certainly overheat and may become very dangerous. As a result of personally experiencing a couple of highly unpleasant incidents of this sort I would suggest adopting the following safety code in respect of all turtle heating and electrical installations:-

  • ALWAYS fit and use an Earth Leakage Circuit Breaker (ELCB) in all animal electrical applications; these are available at low cost from any electrical store. They sense if an electrical shock hazard situation has occurred and cut off the power instantly, before a lethal charge results. They can represent the difference between life and death and in my opinion it is extremely foolish not to make use of them.
  • DO NOT use unprotected glass-encased heaters or thermostats in turtle installations; they simply are not strong enough. If using any submersible heater, protect it by enclosing it in a secondary plastic or metal grill glued to the sides of the tank using aquarium sealant.
  • ANY HEATER which the turtles can touch may cause burns; the same applies to carelessly situated basking lamps. Be careful. Protect submersible heaters with a shield as advised above.

The water area of the tank or pond must be deep enough for the turtles to submerge themselves completely and to be able to swim freely. A land area is also required, and this is usually most conveniently located at one end of the tank. Easy access to the land area must be possible, a sloping ramp is usually the best approach. Beware, however, of fixtures and fittings under which turtles could become trapped. This land area can consist of submerged bricks supporting a peat and gravel surface layer.This is especially critical for female turtles who need somewhere suitable to nest if they develop eggs. In such cases, ensure the surface layer is at least as deep as the turtle's carapace length. To prevent thhe land area becoming saturated with water, the land area can be constructed in a large plastic tray. Above this the basking lamp should be positioned to provide artificial basking facilities.

Overcrowding in tanks is a major contributory factor in the incidence of disease. It is far better to under-stock a tank than to over-stock it. A tank which is crowded will rapidly become fouled and quite probably smelly and unpleasant - for both the terrapins and their keeper. Good filtration helps, but is not a substitute for common sense in stocking; and remember, small turtles can grow very quickly. The golden rule is: the more water volume and fewer turtles you have in a tank or pond - the better.

Land area

The land surface of an aquatic terrarium should comprise both soil and gravel. This is essential; decorations may then be added in the form of logs and plants. These not only look attractive but they provide cover and an important sense of security for the turtles.

Plants & decorations

A selection of plants in the turtle vivarium (both terrestrial and aquatic) look absolutely splendid, of that there is no doubt. What is in doubt is how long they will last. Turtles will often eat these `decorations', or may simply use them as toys and destroy them. In a large tank or pond, the natural ability of the plants to recover might - just might - enable them to survive. Aquatic plants can definitely help to improve and sustain water quality, but are really only of use in large tanks and ponds, therefore, where they should definitely be included. In small tanks they tend not to too very well at all. Artificial, plastic plants are actually quite useful accessories in these situations. They provide good cover, look very attractive, and are easy to sterilise. Choose tough looking ones - fragile varieties will last no time at all. A good compromise is to use a combination of real and artificial plants; the real ones provide water quality enhancement and something for the turtles to nibble, and should be changed regularly. The plastic ones provide secure long-term hiding places which need not be disturbed unless cleaning is required. If turtles do consistently bite pieces out of plastic plant decorations, a potential hazard exists; such material can lead to gut impactions. In these cases, the plants are best dispensed with. However, most turtles and plastic plants co-exist quite happily.

Water area

The water section in most tanks does not need to be very deep - in the majority of cases 150-200 mm will suffice, although larger turtles may require considerably more. Some turtles, most notably Soft-shell turtles, like to burrow into the tank bottom; we normally place a layer of sand and to a depth of about 30-40mm depth on the tank base-plate so that they can express this natural behaviour. It is not true, by the way, that turtkes should be kept only in water no deeper than they are long; in the wild they are found in water several feet deep, and my own turtles live quite happily in a pond which is more than two feet deep. The main problem with keeping turtles in captivity is water hygiene. Turtles are messy feeders and for even a small specimen in a modest vivarium quite powerful filtration will be needed.
By far the best filters are external canister types which use a foam filtration medium; our own aquatic turtle tanks use Fluval model 403 or equivalent units from manufacturers such as Eheim and Magnum. These ensure good water circulation and a high standard of water purity. Nothing is worse than dirty turtle water - it poses not only a health hazard to the turtles, but also - potentially -to their keepers. It is also very smelly and generally unpleasant. Use an effective filter and you will not only keep the water crystal clear but also reduce the manual labour and tedium of frequent water changes.
It is worth noting that what is actually required in a turtle set-up is good quality mechanical and biological filtration. The waste which needs to be removed is far bulkier than that produced by fish and will soon clog up the fine filter `wool' supplied as standard with most filter units intended for fish. We remove this material and instead add extra foam or coarse granular media which is better suited to turtle maintenance conditions.
In our smaller turtle tanks we have found internal foam canister filters excellent at keeping the water clean. These are especially safe for hatchlings and small turtles who may find the turbulent water currents created by more powerful filters uncomfortable. If the foam media becomes clogged with waste, it is easily removed, given a quick rinse under the tap and then replaced. This should be done regularly, or whenever the flow of water through the filter diminishes as a result of waste accumulation.

It is vital that the water in tanks and ponds is well-oxygenated. This helps to keep the bacteria which live in the filters and which digest waste alive and funtioning at peak efficiency. We install several 'airstones' in all of our tanks and ponds to assist aeration.

Another way around the `dirty water' problem is to employ a separate feeding tank; however, this procedure is extremely time consuming, often messy, and obviously requires the filling and emptying of a separate tank or bowl each feeding session. This rapidly becomes a very unwelcome chore, which given the avoidance of overfeeding and provision of adequate filtration in the main tank system is completely unnecessary. I am also not keen on separate feeding tanks as they invariably involve a lot of extra handling for the turtles which can result in stress.

Outdoor and indoor turtle ponds

Alternatives to glass aquarium tanks include indoor or outdoor ponds. Indoor ponds can be extremely attractive and successful, the only drawback being the space required. If the space is available, then they can make a very decorative display feature as well as providing an ideal home for several large terrapins. The framework of the pond can be constructed from wood and then lined with a heavy duty plastic pond liner, or alternatively may be made entirely from fibreglass. Equipped with a waterfall or fountain, and with the surrounding area well planted such a display is most impressive. Outdoor ponds can also be used but the construction of these is obviously a major undertaking. One end of the pond should slope gently to provide ease of access. A shallow area will also provide a differential temperature as it warms up under the sun more readily than the deeper end. The difference may only be 1-2 degrees C but this is sufficient to be noticed by the terrapins. A few logs partially submerged at other places will also provide not only exit points but also basking sites. All terrapins are excellent climbers and are adept at escaping, so good security around the pond area is vital. We suggest allowing at least 1m of ground area all around the pond, surrounded by a cement or brick wall at least 30cm (12 inches) high and further topped with wire mesh. Wire mesh should not be used on lower levels as the terrapins may injure themselves on it - claws can easily become stuck, and delicate noses abrade rather easily. Small terrapins may be viewed as prey by large birds (particularly herons), so these should not be released into open pond areas. Shelters should also be provided, and the surrounding area can be attractively planted. Outdoor ponds are therefore ideal if you have a large number of terrapins and sufficient garden space to permit installation.
Only hardy (temperate) turtles can be kept out of doors, tropical species from warm climates
cannot be kept in this way, unless you live in a tropical or semi-tropical region yourself. Even temperate species will almost certainly require some form of supplementary water heating system on occasions. This form of accommodation is also not really suitable for juvenile or hatchling terrapins - only large and relatively robust adults can be kept in this way. Juveniles are best housed indoors in heated tanks, at least until they have attained a reasonable size.
Ponds intended for year-round use must be at least 1m (3 feet) in depth and must have a large surface area. Ponds which are deep, but which lack surface area, can result in dangerously low levels of oxygenation - especially during hot weather or in the winter. Water oxygenation can be improved using waterfalls, fountains, air stones and external (Koi carp type) pond filters. In outdoor ponds, hardy turtles will hibernate during the cold winter months. Whilst hibernating they do not surface to breath air, but instead absorb oxygen through their skin. In order to avoid anoxia (oxygen starvation), it is vitally important that the pond is adequately oxygenated at all times. Unless you are absolutely certain that your pond is entirely suitable it is usually much safer to overwinter the turtles indoors in properly heated tanks.
It is also important that the pond has a good bottom layer of mud and other sediment as this will be used by the hibernating terrapins for protection from extreme cold. Total freezing of the surface in winter can be prevented by using submersible pond-warmers. These and many other accessories can be obtained from water-garden centres and aquatic mail order suppliers. The catalogues issued by aquatic supply companies can provide a wealth of interesting ideas and often contain many useful items which used imaginatively can greatly improve the quality of a captive turtle's life.


Most temperate aquatic turtles also hibernate in the wild and this can likewise be achieved in captivity; however, it is a relatively advanced procedure requiring a good deal of specialist knowledge and experience on the part of the keeper. There is little or no room for error. Our advice in most cases is to overwinter these animals. In the wild, such turtles usually hibernate in the mud on the bottom of rivers or ponds, but even where the animals are kept in a pond in captivity, it is highly unlikely to be able to provide conditions ideal for such a hibernation; anoxia, or lack of oxygen, is only one of several possible problems which can arise. For safety's sake, unless you are an experienced keeper who is absolutely sure of what you are doing, we would caution against attempts at hibernating any aquatic turtle.

Further reading:

 Lighting for tortoises and turtles

Aquatic Turtle Feeding Guide

Red-Eared Slider facts and disease prevention

Keeping Musk turtles

Mauremys turtles of the Mediterranean - Care and Breeding

Surface mounted ponds - an excellent alternative to glass tanks

Creating 'Natural' environments for aquatic turtles




(c) A. C. Highfield 1992-2002