UVB for Sandfish Skinks
Sandfish skinks are diurnal, which means that they are most active during the day, and they need exposure to visible light and UVB rays in order to be healthy. Of course, unless you have a strategically-placed hole in your roof, natural, unfiltered sunlight is a little difficult to get indoors. Fortunately you can replicate it with a high quality fluorescent tube UVB lamp placed over the lid, about 1/2 to 2/3 of the length of the enclosure. For a 20 gallon enclosure, for example, that would be an 18-24” lamp.
Sandfish are native to northern Africa and the Arabian peninsula, and these areas experience intense sunlight, and correspondingly intense UV readings. Herpers have noted, however, that wild sandfish are typically most active above the sand in the morning and evening, which is when UVI is relatively low. As such, they are classified under Ferguson Zone 1. If you have a Solarmeter 6.5 (recommended), the UVI on the basking surface should be between 1.0-2.0 (personally I prefer to provide the higher end of this range). UVI should be highest at the basking spot and lower in other areas of the enclosure so your lizard has options to choose from.
If you don’t have a Solarmeter, here’s a fair guide to distancing with each bulb type. The given distances are the optimal distance between the lamp and the sandfish’s back when basking:
- Arcadia T5 SO ShadeDweller 7% UVB kit — 8-12″ / 20-30cm
- Arcadia T5 HO Forest 6% — 14-20″ / 35-50cm
- Zoo Med T5 HO Reptisun 5.0 — 14-20″ / 35-50cm
The above estimations assume a ~35% mesh block and come from bulbs installed in Arcadia ProT5 or Vivarium Electronics fixtures. For more details on adjusting basking distance based on mesh obstruction, see the Facebook group Reptile Lighting > Guides > Guide 1: Using T5-HO lamps above a Mesh Screen.
Due to reported unreliability in performance, ReptiFiles does not recommend ANY other brand of UVB bulb at this time. Using other brands of UVB lighting without the use of a Solarmeter 6.5 may negatively affect your sandfish’s health.
Note: Make sure that your UVB lamp fixture doesn’t have a piece of glass or plastic to “protect” the bulb. UVB rays are blocked by glass and plastic, rendering that bulb you just spent so much money on completely useless. Naked UVB bulbs are effective UVB bulbs!
UVB bulbs decay over time, so in order to maintain consistent performance, you will need to replace your bulbs every 12 months. Even if your lamp is still producing light, that doesn’t necessarily mean that it’s working — UVB lamps can still produce visible light even when they’re producing very little UVB!!
Other Lighting for Sandfish Skinks
Considering that sandfish are generally considered to be diurnal (day-active) and mid-day baskers, it is reasonable to assume that they prefer and are stimulated by the presence of bright light in their environment. This assumption is supported by captive observations.
Although UVB lamps and heat lamps (we’ll get to that later) do produce some visible light, they simply don’t produce enough of it to get anywhere close to replicating daytime illumination. For this reason, ReptiFiles strongly recommends adding 6400K or similar full-spectrum T5 HO fluorescent or LED lighting to further illuminate your enclosure.
Here are ReptiFiles’ favorite “daylight” lamps for a 30″ long sandfish terrarium:
- 16” Bio Dude Glow & Grow LED
- 18” Arcadia JungleDawn LED Bar
- Vivarium Electronics T5 Double Bulb Light Strip
DO NOT use colored lights of any kind with your sandfish (red, black, blue, etc.), not even during the night. These can potentially negatively affect your lizard’s mental health by altering their perception of color in their environment. And honestly, it looks weird and unnatural.
How long should the lights be on?
Keep the lights on for 12 hours/day. You can do this by manually turning the lights on and off or by putting them on a timer (I’m in love with smart timers right now! Currently I’m using Kasa smart strips).
Sandfish skinks are native to the scorching deserts of northern Africa, so they prefer very high basking temperatures:
- Basking spot surface temperature: 130-140°F (54-60°C)
- Cool side temperature range: 80-90°F (26-32°C)
The total thermal gradient from basking/warm side to cool side should have temperatures ranging between 140°F to 80°F during the day. For best results, measure temperature a few hours after the heat source has turned on.
Heat sources should be turned off at night so temperatures can drop to 70-80°F (21-26°C).
Sandfish skinks do not need colored light bulbs (red, blue, black, purple, whatever) for “extra heat” at night, and using these can prevent your skink from sleeping well. Contrary to popular belief, reptiles can see red light. How would you like it if someone left the light on while you tried to sleep?
What do you use for heat?
A heat lamp! Heat lamps are the most natural way to create heat for your sandfish because they mimic the way that the sun provides light and heat from above, warming both the air and ground beneath.
If you are using a glass terrarium or other enclosure with a mesh top, I recommend using a dome-style heat lamp fixture with a ceramic socket and built-in lamp dimmer or a dual dome fixture plugged into a rheostat. I prefer:
- Fluker’s Repta Clamp Lamp with Dimmable Switch, 5.5″
- Zoo Med Mini Combo Deep Dome Lamp Fixture with VE Rheostat
There are many different types of heat bulbs available, from reptile-specific brands to floodlight bulbs at your local home improvement store. These are my preferred bulbs for heating sandfish skinks:
If you find yourself frustrated by reptile heat bulbs that keep burning out in less than 2 months, it probably means that you’re either not using it correctly or you bought a defective bulb. Here’s what you should do:
- Wash your hands thoroughly with soap before installing the bulb. Skin oils can potentially reduce lightbulb lifespan.
- Check your heat lamp. Is it rated for at least 150w? Does it have a ceramic socket? If not, that’s likely your problem, as well a fire hazard.
- Ask yourself: Has the lamp taken a fall recently? The filaments in these bulbs are fragile, likely the result of needing to produce UVA. Jostling or falling while the bulb is hot can prematurely break the filament.
- Contact the manufacturer. If you have done everything correctly, it’s likely that you just got a bad bulb. Check the bulb’s warranty, and if it’s still covered, get in touch with the manufacturer to get it replaced free of charge.
This is a common question with no solid answer, sorry! Generally speaking, if you have 6” of sand in a 12-18” tall enclosure, then a 50w halogen should be plenty, and possibly more than enough. Exactly what wattage bulb you will need depends on room temperature, enclosure height, substrate depth, and which bulb you’re using.
If you need more distance, try raising your lamp further above the enclosure with the Zoo Med Reptile Lamp Stand.
- Pro tip: Be sure to buy white or clear bulbs rather than red, blue, black, or whatever other color they’re offering. Colored bulbs do more harm to a reptile than good.
ReptiFiles does not recommend using ceramic heat emitters (CHEs), heat pads, heat tape, or radiant heat panels with this species, as they simply don’t get hot enough for a sandfish’s needs without becoming dangerous.
How do you measure temperature inside a sandfish enclosure?
The best way to measure the temperature of the sand in your enclosure (which is going to be where your sandfish feels the heat) is with an infrared thermometer, aka temp gun. Without getting too technical, this device measures the temperature of surfaces rather than the air like traditional thermometers. For a sandfish that spends most of its time underground, surface temperature is much more important than air temperature.
→ ReptiFiles recommends: Etekcity Lasergrip 774
A digital probe thermometer can be good for measuring air temperature, but analog stick-on thermometers tend to be grossly inaccurate and can put your skink’s health at risk.
What is a temperature gradient, and how do you make one?
A temperature gradient (sometimes also called a thermal gradient or heat gradient in this hobby) is the range of temperatures within your reptile’s enclosure. As ectotherms (cold-blooded animals), reptiles can’t control their body temperature like humans can. Instead, they rely on the temperature of their environment to regulate their body temperature. But instead of seeking one perfect temperature all the time, they move from warm areas to cool areas and back again, depending on what they need.
In order for your sandfish to be healthy, it needs a temperature gradient in its enclosure. The easiest way to do this is by putting the heat lamp on one side of the cage. The side underneath the heat lamp then becomes the warm side, while the opposite becomes the cool side. Temperatures between the two sides will naturally flow from high to low depending on distance from the heat lamp.
Since sandfish skinks are native to some of the driest areas in the world, they don’t need much in the way of humidity. This is one of the reasons why they’re some of the easiest reptiles to keep! That being said, like every other living thing on Earth, they do need water. In the wild, sandfish will seek out areas of higher humidity such as near small bodies of water, under rocks, or pockets of moist sand as needed.
Recreate this in your sandfish’s enclosure by drilling a notch into a thin PVC pipe, and then inserting it vertically until the notch is touching the bottom of the enclosure. Regularly trickle water through this pipe (about once a week or every other week, depending on how fast it dries out) to create a damp layer of sand at the bottom of the enclosure.
Alternatively, you can use a sheet of PVC or stone tile to partition off about 1/4 of the sand, and then keep this area moistened via misting with distilled water. I find using a pressure sprayer like the Exo Terra Mister very helpful for this.
You must also provide a shallow bowl of water for your sandfish, just large enough for it to be able to lay in the dish if it wants (although this is rare). It should be no deeper than 1”. Use tap water or purified drinking water, as distilled or R/O water is not safe to drink. However, distilled and R/O water is ideal for misting.