Care in Captivity
The matamata is not a very common animal in captivity. Virtually no captive bred specimens are available. Adults are most frequently imported. Matamatas are quite expensive, costing between $150 and $800, with most selling in the $400 range. They are not endangered or protected, but are very difficult to find in the wild and not imported in large numbers.
Enclosure
Because of their large size, adult matamatas need large enclosures. A minimum of 75 gallons is usually recommended. As these are not very active turtles and prefer to just sit on the bottom, water depth is very important. The water cannot be deeper than the turtle’s neck is long. This turtle will not swim to the top for air and needs to be able to reach the surface while sitting on the bottom. There is no need to include an area for basking or lights, as these turtles’ normal habitat is murky water and are they are not accustomed to being in a bright environment. Live plants or dead leaves make good additions to their enclosure. They improve water quality, maintain the necessary low pH and soften the water. However, it is very messy and will clog filtration quickly. Matamatas demand a low pH (high acidity) for their water - 6-6.5 is usually recommended (Montoya, A. 1999). I have even been told that going as low as 5 is recommended. There are several ways to decrease pH. Many pet stores sell chemicals specifically for this purpose. A commercial product called Tetra Blackwater Extract is also available. This is added to the water and will lower the pH and make the water darker. Another recommended method is to add peat moss to a box filter (Montoya, A. 1999).
Feeding
Feeding matamatas is fairly simple in principle, so long as you can procure enough fish. Obtaining a large quantity of good fish can be challenging. The most commonly available fish is the common goldfish (Carassius auratus). Unfortunately, according to Montoya (1999) there can be problems associated with feeding large quantities of goldfish to turtles:
Much of the feeding controversy with matamatas concerns goldfish. These are farmed, often in crowded ponds where various chemicals are used to treat algae, the water or sick fish. One concern is the effects of the accumulation of these chemicals over time, notable copper sulfate, which is used for algae removal. Because of these rearing conditions, goldfish are one of the most diseased and illness-prone fish in the aquarium trade. For these reasons they are not considered the top choice as feeder fish.
Finding enough fish to feed an adult matamata is problematic. An adult can consume up to 3,000 to 4,000 small (5-9 cm) fish a year! Another feeding option is to use frozen fish, which may also present a problem of when a fish is frozen. The fish will develop thiaminase, which is an enzyme that degrades vitamin B. Shiners, bait minnows, and tadpoles are other possible diet items. In fact, my matamata has developed a liking for bull froglets.
Water quality
With such a large diet, water filtration is a necessity. Large box filter or external canister filters are the only ones adequate to handle the waste of a matamata. Due to the large amount of waste, ammonia and nitrite levels need to be monitored closely.
There are really only 2 main options for substrate. The first option being smooth pebbles or “river rocks”, the second option is no substrate at all. The rocks make keeping the enclosure clean a little more challenging and there is the risk of the turtle ingesting a rock. Keeping it on no substrate doesn’t look as natural, but is easier to clean. It is a good idea to avoid rough concrete because it can lead to abrasions in the plastron that can develop into shell rot, which is seen occasionally in newly imported animals (Montoya, A. 1999).
Breeding
There has only been one documented case recently of captive breeding in the US (Espenshade, III, W. H. 1990). It is thought that nesting occurs from October to December and 12 to 28 eggs are laid (Ernsnt, C.H. and Barbour, R. W.). Incubation can last as long as 200 days (Montoya, A. 1999). It has also been reported that the egg substrate has to be acidic to help decompose the eggs so the hatchlings can leave (Espenshade III, W.H. 1990). If anyone has had success in breeding matamatas lately, can you please write me at c_fimbriatus@yahoo.com with details on what you did to get the turtles to breed and incubation procedures for the eggs.
More research on the matamata needs to be done, especially in the area of captive breeding. Surprisingly little information on the lives of these animals in the wild is available. Even though people have been able to maintain matamatas in captivity for quite some time, there is still much to learn about this fascinating and bizarre animal we call the matamata.