Shinisaurus crocodilurus / Chinese crocodiletail lizard- Care

Shinisaurus crocodilurus (Ahl, 1930)

By far one of the favorites in our personal collection. This lizard usually has beautiful colors and patterns, a robust head, keeled scales and a tail that resembles that of a crocodile. Clearly adapted to a life in and around the water. When this species just got into the hobby, people had a lot of bad luck, mainly due to the wrong care and the very poor condition of wild-caught animals. However, we have learned a lot and now this species is bred in great amounts. So many that there are more of these lizards in captivity than in the wild. Here, the estimated population is only 800-1000 animals in China. In Vietnam, this number is even lower, it is estimated that fewer than 100 individuals are found in the wild here. In the meantime, this species is very strictly protected and no wild collection is allowed, there are Studbooks, many hobbyists who breed them, Zoological institutions that work with this species and also in their natural habitat there are many breeding, reintroduction and protection projects. Unfortunately, the population is still under pressure. Mainly because the species is used for traditional medicines and the loss of their already small and specific habitat, but unfortunately also by poachers to be sold as a "pet".

Characteristics: The Shinisaurus is a relatively small species, with an adult length averaging 38cm (30-42cm). The tail makes up just over 60% of this total length. They are clearly adapted to their life in and around the water. The tail is clearly laterally flat to ensure sufficient propulsion. The body can be called almost "square". With clearly raised scales at the top of the back. The scales are usually bony and keeled all over the body. The head is relatively short with a wide neck. Clearly built to overwhelm and crush all kinds of invertebrates. The legs are powerful, they are good climbers, there are no webs between the toes to help with swimming. When the animals swim, they push their legs straight along the sides. They have good eyesight and use it while hunting and to spot intruders.

The colors and patterns can clearly differ between populations, but also within a population. There are many different forms. The base color is a form of brown with dark bands. The animals often have a pattern of dark bands on a light background on the underside and sides of the head but can also be almost completely uniform. The ventral side and part of the flanks is often light in color. But can also be dark, yellow, orange or sometimes even bright red (especially with males). The back is often dark and there can be an unclear pattern of bands. The flanks often show a complicated pattern or are covered with irregular spots. The scales here can be different colors of brown, white, red, orange and everything in between. The tail is banded.

There is some difference between the sexes, but it is often difficult to see even in adult animals. There are often no obvious pores around the cloaca like with geckos and “true” lizards. The difference in size is also nihil, although males can be slightly larger / bulkier. The most obvious differences are present in the structure of the head and the colors (especially in the mating period). Males usually have a more robust head and are seen from above wider with a shorter snout. Females, on the other hand, often have a narrower head with a slightly slimmer / pointed snout. The color splendor of males is often more intense and colorful, which can increase during the mating period. However, this is not to say that the females are unable to display beautiful colors, including orange and red. Although this is often less intense or numerous. Note that a male can sometimes look like a female, especially if several animals are present and another male is obviously dominant. Some lines are less colorful as the well-known red white-headed animals. So pay close attention to the mutual interactions.

Origin and habitat:  Shinisaurus crocodilurus is found in "sub-tropical" deciduous forests at 200 to 1500m above sea level. Always near water, for example a stream or pool in the Karst rocks. The areas are difficult to reach due to the dense vegetation. The pools are usually only a few square meters in surface-area with a water depth of 30cm to 300cm. Although we often keep the animals per couple or sometimes trio, in their natural area of ​​origin the animals often live solitary and have each and a relatively small territory, which mainly consists of a number of branches above and along the water. The species is relatively inactive and is mainly found around the water for hunting to hide when they flight. Mating also takes place in the water.

This habitat can be found in some fractioned parts in China in GuangDong and Guangxi (Summer max 40C, winter -5 to 5C). and there is a population in North East Vietnam in Quảng Ninh (max summer temp. 30C, Wintertemp 13-17C). The Vietnamese population has been classified as an subspecies in 2016, now named Shinisaurus crocodilurus vietnamensis. 

Behavior: The activity of this species is relatively low. They are often resting motionless on a trunk, branch or at the water's surface. As soon as a possible prey passes by, the animals quickly run towards it. Most activity takes place during the day, the animals hide at sunset.

There appear to be many forms of social interaction between individuals. Mainly through head nods and shakes and body positions. We are yet to understand most of them. Even young animals can already be very territorial, which will increase especially in males. Note that females can also display mutually dominant behavior. So pay close attention to this if you house several animals together.

Once established, the lizards are not shy. They sit quietly when the caregiver is in the room or in front of the terrarium. The animals quickly learn to accept food from tweezers. In the event of a disturbance, the Shinisaurus quickly jump into the water to hide there.

The terrarium: Shinisaurus are housed  and kept in many different ways when it comes to terrarium setup and size. Although all terrariums in the base are an "aqua terrarium". That is to say, usually 90% to 100% of the bottom surface is water, with in and above it space for the animals to dry up and to reside in and around the water. A few take care of the animals in a setup in which the water part is only a large water bowl. But, these are usually temporary or quarantine setups. Preference is given to well-ventilated, fully planted and furnished terrariums with many hides and drying places.

There are hobbyists who successfully house and breed their animals in a 90x45x60cm Exo-Terra Terrarium per confirmed flock, but this is the absolute minimum. More sensible is a terrarium of, for example, 100x50x80, but ... in this case, bigger is always better. In a terrarium of proposed size, the animals can get away from each other, there is enough space to set up various climbing options and thus also offer sufficient temperature, humidity and UVB gradients.

Water is very important to this lizard. The Shinisaurus regularly sleep there, move around, hunt on the surface, give birth to their young in the water and also mate in the water. Diving sometimes happens while moving, but especially when the animals are startled and want to hide. Hobbyists are successful with water depths from 7cm to 30cm +. Although there is a possibility that young can drown in too deep water at birth, especially if there are not enough possibilities to reach the surface. We recommend a water depth of 10cm to 17.5cm in a terrarium with sub-adult / adult specimens. It is absolutely important that this water is and remains clean. If this is not done, various health complaints can arise. A common complaint is fungi and bacterial infections on the skin / scales, excessive sheds can be an indicator of this. Filtration is therefore sensible but avoid a very strong flow. Internal filtration is usually sufficient if it is properly maintained and partial water changes are regularly carried out. There does not seem to be a preference for specific water values. You can cover the bottom with a thin layer of river sand or coarse rounded pebble. A bare bottom is also possible as this is easier to clean and the Shinisaurus crocodilurus has no direct contact with it. It is wise to fill the water section with many trunks, floating cork plates and aquatic and swamp plants so the animals have many options to move in, around and out of the water.

There are two things to consider when furnishing; hides and climbing opportunities. Shinisaurus have complex (social) behaviors, including interactions. It is important that you provide the animals with enough space to be able to seperate themselves, even if they are a good functioning pair. The hides should be spread over the entire terrarium, both flat on the water surface and in different heights. This can be done with trunks, many hollow cork tubes and by adding a lot of vegetation. Plants that usually do well in the terrarium are Epipremnum, Scindapsus, Ficus pumila etc. Another point is to offer sufficient climbing possibilities. Shinisaurus are always associated with water and they are also adapted to this. But during fieldwork it has been discovered that the lizards also stay on trunks and overhanging branches and also spend the night there. Therefore, offer many options at various heights. This way, the Shinisaurus can always choose the option that suits them best, also when looking for the right temperature, humidity and UVB gradients.

Shinisaurus is seen as a species that likes "low" temperatures. And it is true that prolonged high temperatures can cause stress. But this does not mean that the animals must be kept "cold" constantly. Even if we look at their natural habitat, there is a relatively clear difference between summer and winter temperatures. In the terrarium, the average air temperature in spring and summer should measure around 26C, with a min/max of 23-28C. It is wise to offer a basking spot at 32-35C by means of a heat spot. The animals use this warmer area relatively little, but it remains wise to offer it. The lizards need to be able to thermoregulate well and, for example, gravid females visit this warm place a bit more often. The air humidity should be between 70 and 80%. In the evening it will often increase. It is very important that there is sufficient ventilation and that the animals are not constantly wet. Due to good ventilation and sufficient climbing possibilities, the animals can always dry well. Misting is often not necessary because of all the water that increases humidity through evaporation. But the plants and Shinisaurus will certainly appreciate this. The water temperature itself can measure an average of 22-25C. This will usually happen if the terrarium is heated sufficiently, otherwise you can use an aquarium thermostat heater that protects you well to prevent damage to the heater and animals.

UVB is very important for these lizards. People often use the HID lamps of 35 Watt because they also provide a sunny place. But given that the animals make little use of this and appreciate a more even distribution of the UVB / UVA (and a relatively low UVI), it is advisable to illuminate this HID spotlight with T8 or T5 TL lighting. The output of the T5 lamps is often better and lasts longer. In our own animals we clearly see that this option is appreciated considerably more than only the HID lighting, which is sometimes replaced by a normal heat spot with only UVA to stimulate the basing behavior. So make sure that there is a good light distribution with a UVI of 2.5-3(.5) in the zones closer to the lamps. By means of all climbing branches, plants and shelters, the animals themselves can choose what they prefer. Depending on the season, eluminate 9 to 13.5 hours a day.

This species naturally undergoes a brumation or hibernation. We also mimic these in captivity. Especially if you want to stimulate the overall health and reproduction. If you can let the temperatures drop in their own terrarium and there are enough hides then this may be an option. But many do not have the opportunity to do this. In this case, a hibernation in a refrigerator connected to a thermostat is chosen. Winter temperatures can vary quite clearly in the natural habitat. In the hobby the animals are kept on average at 10C in winter. But temperatures between 6C to 13C can be measured. Preferably place the lizards in a plastic, well-ventilated box with a thick layer of moss. In between, the animals will bury themselves and thus overwinter. Place a water container and keep the moss moist to prevent it from drying out. Check your animals regularly, as they are often active, it is advisable to keep them cooler, or to abort the hibernation to prevent slimming and health problems. A hibernation of 10 to 14 weeks is usually sufficient. Sometimes animals go into hibernation when gravid. They also do this naturally and this does not have to cause complications for a healthy animal.

You can possibly add some fish to the water. The S. crocodilurus will sometimes respond to movement on the surface (feeding response), but often do not reach deeper into the water to grab it. And if they do this then it could be a nice addition to their diet. Fish can be a nice addition, so they can eat and process waste and algae. However, these are an additional burden on the water and the filtration. In addition, they must be able to tolerate the drop in winter temperature. Therefore, we do not recommend doing this, but if you do, try small cold-tolorant Danios, Barbels or Loaches and shrimp.

Diet: There seems to be some difference between their natural diet in different populations. Within the lines that we keep, we also see a clear difference in which food acceptance. The animals naturally eat all kinds of worms, snails, invertebrates and sometimes amphibian larvae that occur around the water. In the stomach contents of the Vietnamese population fish and shrimp was also found, which are probably caught in shallow water.

In captivity worms are by far the favorite. If your Shinisaurus doesn't accept anything else than worms are often what the lizards will respond to. Furthermore they can feed on other larvae such as those of wax moths, caterpillars, silkworms and soldier fly larvae. Other invertebrates that you can feed are crickets (very big difference in acceptance), grasshoppers, mealworms, Zoophoba, dubias and other cockroaches and also snails. We are not yet successful in offering fish.

Young animals can be fed almost daily to build up a good buffer for the winter. After hibernation, adult animals can also be fed relatively well and also take into account any gravid animals. Outside of this you can feed the animals several times, on average three times a week. It is wise to always feed the feeders well before feeding them to your animals in order to ensure optimal nutritional value. You also need to dust the feeders with a calcium supplement, since you offer UVB there will be no need to add Vit. D3.

Reproduction:  This species is Viviparous, which means that the kizards give birth to live young and do not lay eggs. An adaptation that is often seen in (semi) aquatic species. Most mating activity takes place relatively quickly after the necessary hibernation / brumation, but can also occurs later in the year. The gestation lasts an average of 9 months. But can last 7 to more than 12 months. This means that young can sometimes be born just before or after the hibernation. The gestation period is influenced by the temperatures and the food supply. Make sure the female gets enough nutrition and possibly supplement by sometimes offering a day old mouse because of the extra calcium requirement, certainly not too often as these are very fatty. Snails are also a very good source of calcium.

Giving birth always happens in shallow parts in the water. The female hangs on branches that protrude from the water or climbs on a bank along the water and gives birth to her young. The young break out of their amniotic sac and swim directly to the surface. The young are on average 10cm long and clearly look different from the parents. The entire head is lightly colored while the body is very dark. After a few months, they change to their adult appearance.

Young animals can directly exhibit territorial behavior. That is why it is wise to start these individually. You can also place them in a group, then it is important to keep a close eye on the mutual interactions. Provide plenty of hiding places and several places to sunbathe and dry. Feed sufficiently and keep a close eye on whether youngsters are isolated or left behind. With clear repression, it is wise to separate animals.

You can raise the young in simply furnished accommodation, with a shallow layer of water. The further setup may resemble that of the parent animals. Many hobbyists raise the young in plastic containers with high walls. A shallow layer of water with simple filtration by means of an air pump. The setup is simple, lighting is done by a UVB T5 lamp that spans over the bins. A low wattage heat spot provides the necessary sun position and heat gradients.