Site Map

  ©Jan Matiaska, &
  Scott Thomson,


Water Quality and Maintenance for Fly River Turtles

Scott Thomson and Jan Matiaska

The Fly River Turtle (Carettochelys insculpta) is a hard water specialist turtle much like the fish of the African Lakes such as Lake Malawi. The natural conditions from which it comes from is largely rivers that have a limestone base. This means that they are high in carbonates and hence have a high but very stable pH of around 8.0 to 8.3. The KH and GH of the water is around the 18 to 25 dH. Another factor to take into account is that the Fly River Turtle is a scuteless turtle, like softshells (eg. Apalone spinifera) and hence does suffer from a predeliction to fungal and bacterial infections that at their worst can lead to SCUD.

One of the ways that we learn how to look after species is to look to their natural environments and work out what they need based on what seems to restrict their distribution in the wild. Interestingly this species only occurs in limestone based rivers. It only occurs in rivers of high pH, high conductivity and high alkalinity. This means very stable, very clear water. In fact when working on the Daly River with this species there is up to 5 meters of visibility, for us poor humans. Therefore when making enclosures for this species, and in particular the large numbers we were dealing with due to the experiments we were running it became apparent that we needed to duplicate this. See table 1. for the recommended water chemistry parameters for this species.

  Parameter Recommended Level  
  pH (acid - basic scale) 8.0 - 8.3 Basic  
  GH (General Hardness) 18 - 25 dH hard  
  KH (Carbonate Hardness) 4 - 6 meq/L hard  
  Temperature 28 - 30° C. Tropical  
  Table 1. Water Chemistry Parameters for Fly River Turtles.


Making Hardwater

To some degree this will depend on what you have to start with. For example if your tap water has a pH of 7.5 and is already hard you do not have a long way to go. So you do need to know what is coming out of your tap. This is the first step: test kits.

Its time to visit the Aquarium shop. Obviously fish are very sensitive to water quality so we can adopt some of the products used for them to our needs. Don't be afraid to ask the shop owner for advice, they usually do know their aquarium products. A little hint tell them you are keeping a turtle with similar water requirements as the African Lake Cichlids. Tell them the pH and hardness you are after and from their they will know what you need. Our advantage is that we are working with a reptile here that is not as sensitive to water as these fish are.

You can make all the products you need yourself, we are not going to recommend this. If you are a budding chemist then go for it, all the items you need can be bought at the supermarket. But I do recommend you research what you are doing and get some good recipes. Below is a list of the items you will need.

  Product Type Function Example  
  Marine pH Test Kit testing the pH weekly MultiTest: Marine pH & Alkalinty™ (SeaChem)  
  pH Up Buffer Raise the pH and alkalinity Malawi/Victoria Buffer™ (SeaChem)  
  Trace Elements and Salts Increase Hardness Cichlid Lake Salt™ (SeaChem)  

There are some optional extra's as well while you are there, you can if you wish get a water ager or de-chlorinator, this is not essential for turtles, you should consider using activated carbon in your filter. For the purposes of this article I am assuming you have a filtration system set up or in mind. I am not going to discuss this facet. If you have not then you should ensure you do obtain an adequate filter and make sure you have biological filtration as well.

All the products mentioned are examples only, you can use similar alternatives if you wish or need to due to availability. These products all have directions which you should follow aiming for the water chemistry parameters above. Note that the alkalinity, or buffering, of the water may take several days to fully stabilise. Once stable it will need to be monitored weekly. I would recomend that you keep records on each enclosure to ensure you remember what they were so you can see any trends. If you wish to add UV filters or other extra systems feel free to do so.


You should decide upon a regime for water changes, this does need to be done and how often will be a little dependant on the load in the aquarium, how good your filters are and the size of the aquariums. Again these are not fish and a 100% water change does not bother a turtle with the exception of the inconvenience if you interupt it from what it was doing. As long as that water is prepared. So you should plan for the water changes and in the past I kept 200L drums of water with air stones in it that was prepared weeks in advance. If you do not have this option you can mix the water at the time, it will take a considerable amount of buffering to rapidly get the water right. I suggest that you initially take the turtle out of the tank.

As a precaution. If you have a large Fly River Turtle and are placing it in a temporary container get yourself some foam rubber and put this on the base of the container. This species is not very good at keeping its weight distributed and is very prone to pressure sores under the front flippers. These are extremely difficult to treat and become infected easily, best to avoid them.

Reasons for the High pH Regime

We have been asked on numerous occasions why this high pH regime is recommended when the species does seem to do well in neutral water for many people. My immediate thought on this is the question, "are they doing well?" I do not wish to challenge experienced keepers but there does seem to be a bit of luck involved for those animals that are doing ok at lower pH set ups. Also I will say that having very good filtration, UV filters and low stock rates certainly helps. Therefore our main reasons are several fold.

1. The species is naturally restricted to limestone based, fast flowing clear rivers with high pH, high conductivity and a heavy salt load. As an example we used to get electrocuted by the speed boat motors shorting out if the battery charge wires fell in while we worked on the turtles. That means high conductivity. This is what the species prefers.

2. This species is very prone to infection from fungal and bacterial agents. In particular the fungal agents include a group of organisms that thrive in neutral water (6.5 - 7.5) and are largely killed off at the higher pH. Therefore the high pH regime improves the skin condition of the turtle and as this is a scuteless form this is very important. A Fly River Turtle with irritation of the skin on the carapace will rub its own skin off.

3. Freshwater turtles react osmotically with the surrounding water and when the water has a high level of dissolved salts this reduces the workload of the renal system. Turtles absorb water up through the cloaca as well. It is generally a more healthy environment for the captive turtle.


For those who kept fish for years before adventuring into turtles the chemistry lesson has probably been a bit old hat. I (S. Thomson) would like to say that as a former fish keeper (I kept Lake Tanganyika Cichlids, Marines and Australasian Rainbows) there is much that the turtle keeper can learn from some good aquarium design and management. So for everyone else good luck and please look to the rest of the site for additional information.

We did not define all the terms in this paper as there is information on what is meant by the terms pH, GH and KH on the World Chelonian Trust website here.


We would like to thank Scott Davis of SeaChem for his assistance. We would also like to thank all those who have sent us their ideas on how to set up for this species. The senior Author would like to thank Arthur Georges and Bill McCord for discussions and opportunities to work with this species.