Captive husbandry of Carettochelys insculpta
It is possible to keep Carettochelys insculpta in captivity if certain species requirements are met. Here is some basic information and tips, which should provide you with guidelines concerning the captive husbandry of this peculiar species. Be aware, the information below is mainly based on my personal experience and may vary from other sources to some extend. Scott's valuable input is clearly cited.
Because the species is an excellent swimmer, a spacious tank is a must. The size of the tank should allow your specimens to move around freely and, at the same time, to be able to hide if needed. When this species gets frightened, it shoots ahead like a rocket(1) and might hit its head against the wall of the tank. The bigger the tank, the smaller chance the turtle gets injured. As the species can get really aggressive, a bigger tank helps to lower the specimen density. The aggression becomes evident very soon(2) and mostly leads to biting necks and the edge of a carapace. Due to the well developed jaws, the bites can be quite nasty and the affected area can even bleed. Another reason for obtaining a big tanks is that Carettochelys insculpta can grow "up to 22.5 kg in weight and 56.3 cm in length" (Rose, unpublished data). In captivity, the species grows up to 35 cm in length(3), but it still is a size which requires a lot of space. Currently I keep my four Carettochelys juvenile specimens in a glass tank 80 cm / 40 cm / 50 cm [L/W/H](4). Together with the Carettochelys, there are two juvenile specimens of Emydura subglobosa subglobosa. Not only do these two species require more or less the same living conditions(5), I have found out they tolerate each other.
(1) Once I witnessed one juvenile Carettochelys specimen to jump from one tank to another. The tanks were next to each other, sharing one wall and the water-surface level in both tanks was only 2 cm below the top side of the tanks.
(2) I have noticed the aggressive behavior of the species within specimens only 6 months old, but it is possible this behavior appears even earlier.
(3) Out of all the data about captive specimens I have come across, the maximum carapace length was approximately 35 cm.
(4) A bigger tank is due to be built in October (110 cm / 55 cm / 50 cm [L/W/H]) as my specimens are gaining in size quite rapidly.
(5) The distribution regions of these two species (Carettochelys insculpta & Emydura subglobosa subglobosa) actually overlay each other (Papua New Guinea).
The water in the tank should be clean at all times. If a constant in-out-flow cannot be maintained, use a powerful filter(6) and change the water as frequently as possible, because the species is very vulnerable when it comes down to fungi or bacterial infections. On various occasions, Scott told me: "In order to decrease the bacterial and parasitical threat, increase the water pH. You will find the added benefit of both clearer and more stable water quality once you stabilise the pH". In order to keep fresh water at a high pH, Scott suggests to use a coral or crushed sea shell substrate. "It causes lots of buffer every day at first until it stabilises. With attention it will eventually sit on 8.0-8.4 no worries. Make sure you use marine pH test kits and marine buffer [i.e. not sodium carbonate but calcium carbonate]." (Scott Thomson, 2002). I personally use broken sea shells (watch out they are not too sharp), not even crushed, which do the job and are easily collected from the bottom of the tank when I clean it.
Generally, tap water should be fine for filling up your tanks, but this is based on a personal experience and may vary from location to location (in accordance to the quality of water chlorine- and minerals-wise).
Some salt can be added to the water. It is advised to use the stuff available at pet shops that is designed to make artificial sea water. If you decide to use add some salt, do not overdo it. A cup per 150 litres should be enough.
The water temperature should be between 28°C and 32°C. Personally I have my thermostat used in the Carettochelys tank set to 30°C.
If you notice there is something with your water that does not look right, the best advice is to change it as soon as possible.
(6) The usage of a powerful filter does not exclude regular water changes no matter what filer media is used.
If a constant in-out-flow cannot be maintained, a powerful filtration system is a must. Of course the best way of keeping the water clean is to change it as frequently as possible, but this activity can get really time consuming and expensive. A good filtration system does not substitute regular water changes, but at least it expands the intervals between them. No matter whether you decide to use an up-flow or a down-flow filter system, what really counts is the size of the main chamber and the medium used for filtration. The filters which are readily available in pet shops are no good for turtle setups(7) and with a bit of knowledge you can build an effective filter system on your own(8). Basically all you need is a water pump, some kind of chamber (for example an used barrel), a few rubber or plastic pipes and some kind of effective filter medium. As for the choice of the most appropriate and effective medium, there is no medium which could be singled out as a winner as a proof of which there are on going debates among both scientists and public on the pros and cons of various media. It is not an objective of this project to touch these debates in any way, so let's just list most frequently used filter media: carbon, ceramic rings, synthetic wool, sponge, peat, etc.
(7) These filters are mainly designed for fish setups. They have small chambers (which can take up only a limited amount of the filter media) thus the expected effect is reduced. Remember that defecating of turtles species is much greater then that of fish.
(8) On the Internet, there are numerous manuals and tips on how to build a pond/tank filter on your own.
If you want your captive Carettochelys thrive, you will need a set of appliances which are used in order to imitate the natural conditions as much as possible. Here is a list of appliances(9).
- Tank [see the Tank section]
- Small plastic/glass tank - This serves two purposes. First, it can be used as a temporary place or your turtles while you are cleaning the big tank. Secondly, it can be used for your newly acquired specimens that should undergo a quarantine period during which they should be placed separately from your other specimens. The size of the quarantine tank should be chosen according to the number of specimens (and their size) you are planning to keep in it.
- Filter System [see the Filter system section]
- Heater - The water temperature should be between 28°C and 32°C. At night, the temperature can drop down to 26°C. Personally I have my heater used in the Carettochelys tank set to 30°C. If possible, try to keep the heater out of turtles' way, especially the electric wire should be somehow hidden so that turtles do not have access to it.
- Thermometer - To monitor the temperature in your tank, you need a thermometer. There are too types, one being internal, which is attached to a tank wall by a pair of suckers, and one external one, which can be applied to tank wall from the outside as a sticker. I prefer the latter one as it is not an extra obstacle in the tank and it is accurate enough.
- Light system - Even though Carettochelys does not bask, it still needs either day light (applies for outdoor setups) or a full-spectrum light (applies for indoor setups). When I write 'Full Spectrum', I mean all the wavelengths, so do not get cheated for there are many products who's manufacturers claim they produce full spectrum light while they do not. The light is required in order to acquire vitamin D3 that is needed for utilizing Calcium, an essential mineral for the skeleton, carapace and plastron.
- Incubator - You can either buy one or make one yourself.
- Sand - Pre washed river sand can be used as a bottom layer in your tank setup. If the layer is thick enough, it can serve as a hiding or resting place for Carettochelys specimens because they are really good at burying themselves. On several occasions, I have observed this activity at the end of which all that was left to see was the tip of the turtle's proboscis. If the density of your specimens in the tank is too high, I recommend to use sand. If you have spacious tanks/ponds, you might get away without sand as the presence of it makes cleaning your tanks a bit more difficult.
- Salt [see the Water section for details]
- Crushed Sea Shells [see the Water section for details]
(9) We avoid mentioning any particular brand as this project is purely scientific and serves no commercial purposes.
If kept under proper conditions, the Carettochelys has proved to be a relatively hardy species.
All I have dealt with so far were bitten wounds which my specimens caused to each other themselves. The bitten parts usually include neck, rear and side of the carapace rim and folds of skin that run from tail to hind limbs. The frequency and the seriousness of bites depends on the density and the age of specimens in one tank respectively. The higher the density, the more frequently this aggressive behaviour occurs. The older the animals are, the more serious the bites get. The bites on their own do not pose a great danger to your animals; it is the chance of getting infected by bacteria through the open wounds which may be life threatening. It is obvious that to prevent the occurrence of bites, the density of specimens must be lowered and hiding places should be provided. To cure the bitten wounds you must 1) maintain the water in your tank as clean as possible, 2) increase the water pH above 8.0(10) and 3) apply some anti-infection solution to the bitten parts (i.e. Betadine - 10% iodine solution).
There are several reports on how the Carettochelys species is prone to suffer from fungal disorder, one of which says: "Hatchling and sub-adult specimens are particularly susceptible to fungal white spot (Sphagnalium sp.) which if not treated promptly, kills young animals within a week (Mike Palmer-Allen, pers. comm.). It can be effectively treated externally by removing all loose skin and scabs and treating liberally with 1% Mercurichrome (Windholtz et al., 1983: 5698) or Acriflavine Solution (Windhotlz et al., 1983: 116), which is allowed to dry on the skin before the animals are returned to the tank." (Georges & Rose 1993)
(10) See what Scott Thomson has to say on this topic in the Water section.
I have no personal experience with captive breeding of the Carettochelys species, but Oliver Römpp has written to me that captive breeding occurred at both the Bronx ZOO, NY, USA and the Zoological Garden Wilhelma, Stuttgart, Germany. For more information please see Oliver's section about Carettochelys at http://www.chelodina.com/10.htm.
With the information above, you should provide your Carettochelys specimens with proper care - under which they should thrive. If you have any comments or questions regarding the captive husbandry of this peculiar species, please contact us. We will be more than happy to assist you. Watch out for updates of this care-sheet because it is meant to be a live document and new stuff will be added as you ask new questions which are not already answered in the paragraphs above.