Caging For Aquatic Reptiles
Dr. Nancy Anderson
Imagine living in a house where you alternately shivered and sweltered, bumped into the walls every time you moved around and had no place to sit down and relax. Now imagine never being able to leave the house on your own.
Pretty stressful way to live, isn't it? Your reptile can get even more stressed if his cage isn't the right size or quality.
Cages should be nonabrasive, escape proof, leak proof, well insulated, easy to clean, and roomy. Cages should be structurally sound and able to handle the weight of water in the cage. Aquariums, plastic sweater boxes, fiberglass enclosures, and large plastic water troughs work well. Most plastic and glass enclosures can be fitted with plugs or valves that allow the enclosure to be drained from the bottom. If a floor drain is available, this feature helps in cleaning and minimizes the need to transport heavy water-filled cages.
Cramped quarters induce stress. Make sure there are both adequate land and water areas. Most turtle species will require large water areas in their enclosures with smaller basking and haul out zones. A starting rule of thumb is 1 gallon of water per square inch of carapace. Most aquatic snake or tropical lizard species will require large land areas with smaller water areas for soaking and/or hunting.
All aquatic reptiles except sea snakes and sea turtles need adequate basking space. Most "water" turtles will drown secondary to exhaustion if not allowed to rest out of the water. An increased incidence of skin disease is also seen in reptiles not allowed to bask under UV light.
A frequent problem in group tanks is unexplained deaths of smaller animals. The losses are often eliminated by the addition of several basking areas. This allows the smaller reptiles to rest even when dominant individuals are defending their territories. Make sure that it is easy for aquatic reptiles to climb onto land areas.
It is important to keep the land area mostly dry. If it becomes saturated, it's not really land. The easiest way to maintain the land area is to design the cage with an impervious barrier (plastic or glass) between the water pool and the land area. Placing materials that are able to drain easily (large gravel, large piece of non-porous wood, or plastic turf) between the water and the land area prevents the animal from bringing large amounts of water onto the land area.
Provide cage furniture to provide visual security. Plastic containers, clay pots, and plastic plants work well. Access to hiding places allows reptiles to relax and prevents cage pacing.
Large stone gravel and bark chips can be used in the land area. These substrates need to be changed or cleaned at least once a month, which can be expensive and/or time consuming. Sand, kitty litter, corn cobs and regular Astro turf are not recommended substrates for land/water tanks because they hold moisture and promote growth of bacteria.
Water Quality and Heat
Overpopulation causes major difficulties in maintaining water quality, and strict attention to water quality is essential for the water portion of the enclosure. Depending on the system, the enclosure should be emptied of water, washed with soap and water, rinsed well, and disinfected with bleach once a week to once every other month. Although cage furniture such as plastic aquatic plants and large rocks are welcome additions to most tanks, most people do not use substrates such as gravel on the bottom of the water portion tanks, due to difficulty in cleaning.
In between these major cleanings, use of a filter system or FREQUENT water changes are a must. Never use an under-gravel filter. The waste load is too great for these normally aerobic filters. The result is buildup of anaerobic toxins in the gravel. Disturbance of the gravel or an overturn of tank water allows release of toxins that kill tank inhabitants.
An out of tank biologic filter works best. Even so, the sand, gravel, or fibers need to be frequently back flushed to remove gross debris and often cannot handle both fecal and discarded food loads. Pump/filter size recommendations are generally made for tropical fish. Depending on the density of animals in the tank and the amount of food and fecal load, you will need to increase the recommendation by at least a factor of 3.
To decrease biological load on the filter, offer food items for limited periods in a separate tank then return the reptile to its usual enclosure. The feeding tank does not need a filter because the water is completely changed before and after each feeding session and/or group of animals. The feeding tank is then disinfected and allowed to dry to prevent waste buildup and transmission of disease. This method of feeding minimizes wastage of food and allows food consumption to be closely monitored. An easy way to offer a variety of water depths is to set the enclosure at an angle so that the water goes from shallow at the land end of the tank to deep at the opposite end.
The air temperature of the cage should be maintained as a gradient incorporating as much of the POT as possible. One of the easiest methods of accomplishing this is to place a heat lamp at one end of the enclosure. Annual and daily temperature fluctuations may be required by some species to maintain health and stimulate breeding. The heat source should be able to heat the ambient temperature to the desired level while ensuring that the surface temperature at the hottest spot is just less than the high end of POT. (See cage husbandry for details).
It is imperative that the heat lamp and electrical supply be placed in dry areas to avoid electrocution and fires. ANY heating elements that have the potential to attain temperatures over 105 F need to be out of reach of reptiles. ROUTINELY test the thermostats on heating devices as malfunctioning thermostats cause animal deaths and fires.
Water temperature is also very important. A RELIABLE, waterproof heater is essential. Electric shock will not only kill animals in the tank, but also human caretakers. In addition, malfunctions resulting in overheating or failure to heat a tank have killed many aquatic animals. In small tanks, an aquarium heater with an IN WATER thermostat can work well and provides a temperature gradient. Heaters with thermostats on top may underheat or overheat the water because it measures the air temperature and not the water temperature. Take care to ensure tank inhabitants will not burn themselves if they decide to wrap around the heater. This is most easily accomplished by screening the heater. Water temperature in larger enclosures can be maintained by keeping the room temperature at the lower end of a desired temperature range and using infrared lights or heaters at one end to maintain a gradient.
Most aquatic reptiles require ultraviolet light (280 - 315 nm) to synthesize vitamin D3. Ten to 14 hours of light AND dark should be provided daily. See the cage husbandry section for more details.