Water dragons are medium sized lizards resembling small iguanas. Their moderate size, attractive appearance and good personalities have made them popular reptile pets. However their need of a partially aquatic habitat, strong heat and UV light requirements, complex diet, and tendencies for self mutilation make them one of the more challenging lizards to keep healthy in captivity.
Dragons are mostly carnivorous and prefer live prey. Good dietary items include earthworms (nightcrawlers, not redworms or compost worms), slugs (not water snails), small live fish (fed in a shallow bowl of water to allow the lizard to catch them), pinkie mice, and some silkworms and crickets. Feed the crickets a high calcium "gut loading" cricket diet (T-Rex is the best product currently) for 2 days prior to using crickets as food, or they will be calcium deficient. Mealworms and waxworms are nutritionally poor and should be avoided. Healthy dragons will also eat some vegetables, especially leafy greens, including dandelions, kale, collards, mustard greens, green leaf lettuce, and papaya. Ideally use a nutritional guide to choose veggies with good calcium/phosphorous content.
Vitamin + mineral supplements should be used sparingly. Achieving a healthy balance with supplements is difficult. Never mix products; use a balanced vitamin-mineral powder with many vitamins + calcium and phosphorous provided, and put a tiny pinch on the food once weekly, no more. Reptocal and Reptivite are 2 brands which offer balanced formulations. Overdosing is a common problem with powdered supplements; a safer way to supplement is to use a commercial food such as a bearded dragon or juvenile iguana pellet, which can be crushed or ground to a powder, then sprinkled on worms or vegetables. The pellets contain vitamins and minerals at low concentrations so overdosage is not a risk. Crushed food can be used daily as a supplement to the diet.
Try to duplicate natural conditions. Large terrariums are best.. The most important factors are heat & light. The ideal daytime air temperature is 80°-92°F; temperature readings must be taken in the shade away from heat sources to be accurate. Below 80°F or above 100°F can cause stress and failure to thrive. The cage sides and top should be mostly solid, not screen, in order to trap heat. A reptile heat pad placed under the terrarium is one heating method. Hot rocks provide heat but must be covered to prevent direct contact which may burn the lizard. Heat lamps are useful but must be at a safe distance to prevent burns (at least 18 inches usually). Heat lamps must not be bright if used at night; the best are lightless ceramic-coated lamps such as made by Pearlco or Flukers; dim purple or red coated night bulbs may also be used. Monitor cage temperature at several spots with good mercury or dial type thermometers; avoid color strip thermometers which stick to the cage wall as they are not accurate. The terrarium can have a warmer side approaching 92°F, and a cooler area around 80°F. If the cage temperature is uniform then aim at 85°F as an ideal temperature. Do not let the temperature fall below 75°F at night.
A spacious swimming area should be provided. Aquarium designs can be fancy with large landscaped pools and water filters similar to a fish tank. A simpler method uses a large plastic or steel water container that covers part of the cage bottom. The water container can be easily lifted out and the water changed without disrupting the dry part of the tank. Dragons will drink while swimming but also defecate in the water. Without a filter system the water should be changed daily to keep it clean.
Be sure your lizard can easily climb in and out of the water. The dragon should spend most of its time out of the water basking. Basking allows the pet to dry between baths, to warm its body, and to absorb UV light. Artificial turf makes good flooring for the dry area as it can be cleaned and reused, and it can’t be eaten. Sand, small gravel, corn cob, wood chips, etc may be eaten and cause bowel blockages; if used they must be changed regularly when soiled.
Lighting requires special attention. You must provide both visible (white) light and ultraviolet light in the 280-320 nm spectrum (called UV-B). This mimics outdoor sunlight which dragons require. Our climate provides too little sunlight, and window glass or plexiglass filters out most of the sun’s UV rays. Lack of proper lighting causes poor or picky appetites, poor growth, and bone disease. Provide correct lighting with a fluorescent "full spectrum" light. Reptisun (made by Zoo med) and Reptile D-Light provide strong UV levels; other brands with adequate UV output include Verilux, Reptile Daylight (Energy Savers Unlimited), Reptiglo, Reptasun (by Flukers), and Vita Lite. These are all fluorescent tubes; in general no regular incandescent bulb produces good UV light. These lights have a limited effective lifespan and should be changed every 6-8 months when in use. A good day length is 12-14 hours of light. These lights won’t cause burns, and they need to be close to the pet to be effective, usually closer than the length of the light bulb. (A 24 inch tube should be within 18 inches of the lizard to be effective). Avoid plastic or glass barriers between the light and the pet. Minimize hiding from the light (such as in a dark cave); instead provide hiding shelter behind a plant or rock where the light is still strong, or cover part of the transparent cage wall with paper to allow hiding in that area.
More recently some full spectrum incandescent (screw type) round bulbs have appeared which do produce strong UV levels. These resemble regular light bulbs but are actually mercury vapor lamps; they produce high UV output and heat, so must be kept at a safe distance (at least 18-24 inches away). Their effective life span is uncertain; replace them yearly to be safe. These devices typically cost $45-$100, and when shut off must have a "cool down" period before they can be turned back on. Other "full spectrum" round bulbs which cost less and require no "cool down" cycle are simple filament- type bulbs and do not produce good UV output.