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- Green Water Dragon
Physignathus cocincinus
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- "Ping," a large male owned by C. Asenjo
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- Taxonomy
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- Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Subclass: Lepidosauria
- Order: Squamata
- Suborder: Sauria
- Infraorder: Iguania
- Family: Agamidae
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- Genus: Physignathus
- Species: cocincinus
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I. Introduction
A popular pet store lizard, the Green Water Dragon (Physignathus cocincinus) is a beautiful, personable lizard, but it not suitable for beginners. Males may grow to about 90 cm (3 feet) long, and females about 60 cm (2 feet) long- about half of their length is made up of their tail, and need a very large environment to match their size and activity levels. They can be curious, docile lizards, although feisty, flighty individuals that are not hesitant to smash into enclosure walls out of fright are not infrequent. Captive water dragons have a lifespan from 10-20 years, so they are a long commitment.
They are also known as the Asian, Thai or Chinese Water Dragon. Water dragons belong to the large family Agamidae, shared by other familiar lizards like Bearded Dragons (Pogona sp.), Mountain Horned Dragons (Acanthosaura sp.) and Uromastyx ( Uromastyx sp.). They are found in southeastern Asia, through Thailand, Cambodia, Vietnam and southern China, in tropical forests and typically close to water.
The colours on a water dragon can be quite beautiful. When active and healthy, water dragons are often a bright, mint green with lateral white, blue or tan stripes on its back, a whitish belly and white throat sometimes accented with peach or pink. A black band is present over the eye, and the head sometimes has some light blue colouration. The tail is long, laterally compressed and patterned with alternating dark and light bands. They have a pronounced nuchal, dorsal and caudal crest and spines that are larger in the male and accompanied by a bulkier body overall and large jowls.
II. Behaviour
Like most agamids, water dragons are visually-oriented lizards. They communicate with each other by head bobbing, arm waving, tail-flicking and puffing out their throats. Head bobbing it typically a territorial or courtship display, throat-puffing is a defensive or territorial display, tail-flicking seems to be done out of annoyance, and arm waving is a sign of submission.
Water dragons are often bright, alert, yet docile lizards that do not seem to mind being held or petted. Some water dragons eagerly seek out their owner and lounge nearby or on the person's body. They rarely tend to be aggressive unless provoked with rough handling or if the animal is already uncomfortable due to stress or an underlying health problem or injury. Water dragons' bites seldom break the skin, because although they have sharp teeth and rather strong jaws, they seem to give “warning” bites instead of intentionally causing damage.
Like most lizards, water dragons can autotomize their tail if they feel threatened. This defense mechanism, called caudal autotomy, occurs as a sort of "last ditch" effort for the lizard to escape a predator. Its tail breaks off, and the severed piece proceeds to twitch for several minutes afterwards (due to excited nerves left in the tail). This is supposed to distract the predator while the lizard escapes. The tail can regenerate after time, however the re-grown portion of the tail will not be the same colour or have the same texture as the original tail.
III. Diet
These are omnivorous reptiles. The bulk of their diet consists of animal matter, like various invertebrates and occasionally mice or fish.
As far as insects go, gut-loaded mealworms, crickets, cockroaches, earthworms (nightcrawlers and red wigglers- most water dragons relish earthworms) and silkworms (listed from worst to best) make a decent staple diet. The diet can be occasionally supplemented with more energy-dense prey like wax worms, butter worms, horn worms, pre-killed pinky mice, and feeder fish such as guppies (Lebistes reticulates or Poecilia reticulata) and rosy red minnows (Pimephales promelas).
Goldfish are poor feeder animals. Not only are pet store feeder goldfish often sick and parasite-infested, goldfish (and other carp) naturally contain a chemical called thiaminase. Thiaminase is an enzyme that destroys thiamine, also known as vitamin B12 . Feeding goldfish regularly will usually result in a vitamin B deficiency. Overall, it's safer to just stay away from goldfish.
Although many mature dragons will not accept fruits or vegetables, if they are fed portions when they are young they tend to keep this habit as they age. The “vegetarian” part of their diet can be similar to a salad prepared for a green iguana. Dark leafy greens like collards, dandelions, turnip greens, mustard greens and escarole should be a part of the greenery offered. Other vegetables like butternut squash, sweet potato, parsnip, yucca, green beans, snow peas, and acorn squash can be mixed in. Sweet, soft, bright fruits like mango, peach, banana, strawberry, papaya, fig and raspberry add colour, flavour, moisture and a bit of vitamins. All fruits and vegetables should be shredded or chopped into small pieces.
Fruits and vegetables are not a particularly large part of the diet, and if your dragon refuses to eat them it is not a grave concern. Animal matter should make up no less than 60-70% of their diet. The remaining 30-40%, if not less (for finicky eaters) can be taken up by fruits and vegetables.
No matter what type of food you are feeding, variety helps. Supplementing the diet with richer food items occasionally is good practice, although it should not be done too frequently as an obese water dragon may result. Instead of giving treats often, try feeding two or three different staple feeders, alternating throughout the week. Not only is this healthier for the dragon, but it helps prevent a dragon that will either refuse to eat anything but its favourite prey, and on the opposite end will help stop it from getting tired of the staple feeder!
Supplementing the diet with vitamin and mineral powders is debatable. Theoretically, if all prey is properly gut-loaded, then supplements are not necessary to fill in the nutritional gaps. But, we do not know exactly how much of each vitamin or mineral water dragons (or any reptile) need daily, so this is all just guess work. Because most insects have a very poor calcium to phosphorus ratio, and this ratio in an omnivore's diet should be from 1:1 to 2:1, supplementing with a calcium-only powder frequently (2-4 times a week) is recommended for a stable adult. Growing juveniles and gravid females should be supplemented with calcium 4-7 times a week. Vitamin supplements should be sprinkled on their food 1-2 times a week for healthy adults, and 2-3 times a week for growing juveniles. It is very possible to overdo supplements, and too much is just as bad as too little.
IV. Housing
Water dragons need a spacious enclosure that allows room for climbing, a large water dish that they can soak and swim in, and keep a tropical heat and humidity. This can be done with aquariums, but a custom-built enclosure is usually the best choice.
As previously stated, these lizards need a lot of space. Arboreal lizards like water dragons need an enclosure that is at least twice their length tall, one and a half times their length long, and at least as wide as they are long. This means that an enclosure for a fully-grown water dragon should be close to 2 m tall, 1.3 m long, and 0.9 m wide (6 feet tall, 4 feet long and 3 feet wide). For more than one dragon, add half of that space for each dragon (keep in mind that males cannot be housed together because of territoriality issues).
These lizards live forests near bodies of water; this can be duplicated in captivity. A tall enclosure is useless unless you provide branches and shelves for the dragon to make use of vertical space, and these lizards love to climb so it is guaranteed that they will. Branches can be oriented vertically, diagonally, and some horizontally for resting places (equally, you could install shelves for resting spots). Any horizontal resting and basking spots should be at least one and a half times the width of the lizard so that they may rest comfortably. Design basking spots so that they come within 30 cm (12”) of the UVB-producing bulbs.
A large water area where the dragon may swim is very important. True to their name, these lizards love water, and aside from defecating in it, they will spend a lot of time in water, so the water should be kept as clean as possible. There are several options for water areas: A large tub that can be lifted out of the enclosure to be changed and cleaned can be cumbersome, especially since the water should be changed every one to two days (and whenever soiled with fecal matter). A water area built into the enclosure bottom is another possibility. Seriously consider adding a drain so that the water can be changed more easily. Adding an airstone can help keep the water fresh, but is no substitute for frequent changes. A filter can be useful in keeping the water clean, and can help remove the amount of waste in the water between changes, but even with a powerful filter, the water must be changed often. Place rocks in the water area so that the dragon can easily climb out, as even water dragons can get tired of swimming and drown when exhausted.
Live plants can add a lot to the enclosure, like hiding spots, climbing places, humidity and beauty. Not all plants are suitable, however, since some are toxic and should be avoided completely, and some are too delicate to withstand a dragon's abuse and are a waste of money to keep replacing. Tough, hardy, nontoxic plants like Devil's ivy pothos, philodendrons, dracaenae (like the Madagascar dragon tree and corn plant dracaena) , hibiscus, some bromeliads, spider plants and sansvierias (snake plants) have been used with success in water dragon enclosures. All plants to be used in the enclosure should be repotted into a sterile, plain potting soil free of fertilizers, pesticides, vermiculite and perlite (small Styrofoam balls). The entire plant should be rinsed several times in lukewarm water to remove any pesticide residue from the nursery. Inspect the plants before purchase for pests like slugs, aphids and others. Once in the enclosure, maintain the plants according to their appropriate needs. Even tough plants like the ones above might need replacing after a dragon has romped around on them for a while! Fake plants can also be used (and are less work), and a mix of fake and live plants has been found to work very well.
Substrate can be as simple as indoor/outdoor carpeting cut to fit the enclosure bottom, or a more elaborate, natural mix of sand and earth. Carpeting is a favourite of many keepers, as it is cheap, easy to replace and clean, and safe. A moist, 50/50 sand and plain soil mix with or without cypress mulch added is a more natural choice. Some vets and owners swear by sheet substrates like carpet, newspaper, paper towel or butcher paper, as any substrate made up of many little bits (termed particulate substrate) risks being eaten by the lizard and causing a fatal impaction in its digestive system. Problems with the sand and soil mix seem to occur less frequently than with other, very unsafe substrate, like woodchips, crushed corn cob, crushed walnut shells, and wood shavings. It is more difficult to spot clean of waste, and the whole substrate should be changed every few months (which can get expensive).
V. Heating, Lighting, and Humidity
Daytime temperatures should range from 29-32°C (84-88°F) with a basking spot of 35°C (95°F), and at night the entire enclosure should fall no lower than 25°C (75°F). All heating devices should be placed completely out of the animal's reach and there should be a screen barrier between all devices and the rest of the habitat. Plain incandescent bulbs can be used for daytime heat, but ceramic heat emitters can also be used for 24-hour heat if your house gets too cool at night.
During the day they require a UVA/UVB producing light. The fluorescent Zoo Med's ReptiSun 5.0 or IguanaLight 5.0, as well as Exo-Terra's ReptiGlo 5.0 are good brands, along with VitaLite. All lighting fixtures should be placed behind screen. Please note that glass and plastic will filter vital UVB light. Allow the lizards a photoperiod of 12-14 hours. These bulbs should be replaced every 6-8 months.
Humidity in the tank can range from 60-80%, and can be achieved by misting daily, using live plants and having a large water area.
Last modified: Sunday, June 11, 2006
Sources:
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Hernandez-Divers SJ. 2002. “Care of the Thai Water Dragon, Physignathus cocincinus.” J Herpe Med Surg. 12(2):45 Summer 2002 Client Handout. Available online at <http://www.arav.org/Journals/JA018970.htm>
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Manthey U and N Schuster . 1996. Agamid Lizards. New Jersey : T.F.H Publications.
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Power, T. 2005. Tricia's Chinese Water Dragon, Reptile and Amphibian Care Page. "Care of the Chinese Water Dragon." <http://triciaswaterdragon.com/dragoncr.htm>
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