AQUATIC TURTLE
CARE BASICS
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.
Lighting
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.
Heating
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.
Hibernation
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
Red-Eared Slider facts and disease prevention
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