Skip to content
Pet Environment

UVB lighting · Questions

Do reptiles and amphibians need UVB?

Most do. Of the 26 reptiles and amphibians we cover, our guides call for a UVB lamp for 21, recommend one for 2 (kingsnake and milk snake), list it as optional for 1 (dart frog) and don't need it for 2 (axolotl and African dwarf frog).

By the Pet Environment editorial team · Published November 4, 2026 · Care guidance, not veterinary advice

What UVB does

Under UVB light, a reptile's skin makes vitamin D3. The body needs vitamin D3 to absorb and use calcium. Without enough of it, or without enough calcium in the diet, bones stay soft.

The Merck Veterinary Manual calls that condition, secondary nutritional hyperparathyroidism (usually called metabolic bone disease), the most common bone disease seen in reptile practice. It lists poor diet (too little calcium for the phosphorus, too little vitamin D3) and poor husbandry, including no UVB and too little heat, as causes. Signs include not eating, lethargy, trouble walking, a swollen or bent jaw or limbs, fractures and muscle twitching. An animal showing any of these needs an exotics vet, not a new bulb.

A vitamin D3 supplement is the other route to the same vitamin. That is why keepers argue about the animals in the middle of the table below: the ones that may get by on a supplement, but measurably make their own vitamin D3 when they have UVB.

How much: the four UV zones

Researchers group reptiles and amphibians into four zones by how much sun they take in the wild. The UV index (UVI) is what a UV meter reads at the animal. “Range” is the gradient across the enclosure; “brightest spot” is the top of it, at the basking spot. From the UV-Tool (Baines et al., 2016), which summarises Ferguson et al. (2010).

  • Zone 1Crepuscular or shade dwellerRange 0–0.7Brightest 0.6–1.4
  • Zone 2Partial sun, occasional baskerRange 0.7–1.0Brightest 1.1–3.0
  • Zone 3Open or partial sun baskerRange 1.0–2.6Brightest 2.9–7.4
  • Zone 4Mid-day sun baskerRange 2.6–3.5Brightest 4.5–9.5

Night-active animals are not automatically zone-free. The same paper notes that skin from a nocturnal house gecko made vitamin D3 eight times more efficiently than skin from a day-active desert lizard, and that leopard geckos and corn snakes both make vitamin D3 under low-level UVB. Its advice for shade and dusk species is a low, zone 1 gradient with a retreat to sleep in, rather than no UVB at all.

Every reptile and amphibian we cover

What each care guide calls for, read straight from the guide, so this table and those pages always agree. A UV index appears where the guide states one. Tap an animal for its full setup.

  • Bearded dragonReptileYesnot statedT5 HO 10-12% linear desert bulb spanning 1/2 to 2/3 of enclosure length
  • Ball pythonReptileYesnot statedLinear T5 HO Ferguson Zone 1-2 (2-6% UVB) bulb spanning 1/2 of enclosure length
  • Leopard geckoReptileYesUVI 0.5–1.5Low-output 2.5-7% T5 linear tube (Ferguson Zone 1, UVI 0.5-1.5; 0.5-0.7 for albino morphs) covering 1/2 of the enclosure length Do leopard geckos need UVB? →
  • Corn snakeReptileYesUVI 2.0–3.0T5 HO 5-6% linear tube (UVI 2.0-3.0 at the basking spot) covering 1/2 of enclosure
  • Red-eared sliderReptileYesUVI 3.0–4.0T5 HO 10-12% linear tube (UVI 3.0-4.0 at the basking spot) spanning 50-75% of the enclosure length over the basking area
  • AxolotlAmphibianNot needednot statednot required
  • Crested geckoReptileYesUVI 1.0–2.0Low-output 2.5-7% T5 linear tube (UVI 1.0-2.0 at the basking branch) mounted over the top mesh
  • Veiled chameleonReptileYesnot statedT5 HO 6% or 10.0 linear tube spanning 1/2 to 2/3 of top ceiling mesh
  • Russian tortoiseReptileYesnot statedT5 HO 10-12% linear tube fixture covering 1/2 to 2/3 of enclosure length
  • Blue-tongue skinkReptileYesnot statedT5 HO 10-12% linear tube covering 1/2 of the enclosure length
  • Sulcata tortoiseReptileYesnot statedT5 HO 10-12% linear tube covering 1/2 of the indoor enclosure length
  • Box turtleReptileYesnot statedT5 HO 6% or 5.0 linear tube over the warm half, about 13-14 in above the basking spot through mesh
  • Pacman frogAmphibianYesnot statedLinear T5 HO 2.4–6% (Ferguson Zone 1) covering 1/2 of enclosure length
  • Green iguanaReptileYesUVI 3–4T5 HO 12-14% desert-strength tubes (or ReptiSun 10.0) spanning 1/2 to 2/3 of the enclosure, aiming for UVI 3-4 at the basking branch
  • White's tree frogAmphibianYesnot statedLow-output UVB, such as an Arcadia ShadeDweller T5 kit or a 5-6% T5 HO tube over the screen, with the frog's top branch at least 6 in below it
  • Boa constrictorReptileYesnot statedT5 HO 5-6% linear tube covering 1/2 of the enclosure length
  • Gargoyle geckoReptileYesUVI 1.0–2.0Low-output T5 tube, such as an Arcadia ShadeDweller or a 5-6% T5 HO, giving UVI 1.0-2.0 at the top branch and spanning about half the enclosure
  • Dart frogAmphibianOptionalnot statedOptional low-output UVB (T5 HO 2.4-6% shade-dweller tube); a 6500K LED plant light is essential for the live plants
  • Argentine teguReptileYesnot statedT5 HO 10-12% linear tube (e.g. ReptiSun 10.0 or Arcadia 12%) over the basking area, covering about half the enclosure length
  • Hognose snakeReptileYesnot statedT5 HO 5-6% linear tube covering 1/2 to 2/3 of enclosure length
  • Musk turtleReptileYesnot statedT5 HO 5.0 / 6% linear tube lamp spanning 1/2 of tank length
  • KingsnakeReptileRecommendednot statedRecommended: T5 HO 5.0 or 6% linear tube (e.g., ReptiSun 5.0 or Arcadia Forest 6%) spanning about half the enclosure length on the warm side
  • Milk snakeReptileRecommendednot statedRecommended: T5 HO 5.0 or 6% linear tube (e.g., ReptiSun 5.0 or Arcadia Forest 6%) spanning about half the enclosure on the warm side
  • African fat-tailed geckoReptileYesnot statedLow-level T5 HO linear UVB (e.g., Arcadia ShadeDweller 7% or ReptiSun 5.0) covering about half the enclosure length
  • UromastyxReptileYesUVI 4.5–6Strong T5 HO 12-14% linear tube (e.g., Arcadia Dragon 14%) about half the enclosure length over the basking area; aim for UVI 4.5-6
  • African dwarf frogAmphibianNot needednot statednot required

What applies to every animal

  • Glass and clear plastic block UVB. In the UV-Tool's measurements, ordinary 4 mm window glass let through 0.4% of UVB at 300 nm. Never put a lid, a window or a plastic cover between the lamp and the animal.
  • Mesh blocks some of it too, roughly 30–50% for most terrarium screen. Allow for it in the distance, or measure.
  • Give shade. The UV-Tool calls shade vital for every species, whatever its zone: the UVB should fall to zero in a retreat away from the lamp, so the animal chooses its own dose.
  • Light from above. Mount lamps over the animal, not beside it, so the brow shades the eyes.
  • Albino and pale morphs need less. Melanin absorbs UV, so animals with little pigment take more of it into the body. Run them at the low end of their zone.
  • Bulbs fade before they look dim. Replace linear T5 tubes about every 12 months, or on the maker's schedule.

Choosing the lamp

A linear T5 HO tube in a reflector, spanning about half to two thirds of the enclosure, is the default for almost every animal above. Compact coil bulbs light only a small patch and fade quickly, so they are the wrong choice even in a small enclosure. Distance matters as much as the percentage on the box, and a UV index meter is the only way to know what reaches the basking spot.

Reptile UVB lighting: which tube, what strength, how far away covers each lamp type and lists the UVB lamp on every animal's checklist, with typical prices.

Related: reptile heat lamps and thermostats, because a basking spot needs heat and UVB in the same place.

Sources

The table comes from our care guides, each of which lists its own sources. The lamp advice (mesh loss, replacement, coverage) comes from our UVB lighting guide and its sources. The rest comes from these, read November 4, 2026. Care guidance, not veterinary advice: when an animal is unwell, see an exotics vet. How we make these guides.

  1. 1Baines F. et al. (2016). How much UV-B does my reptile need? The UV-Tool, a guide to the selection of UV lighting for reptiles and amphibians in captivity. Journal of Zoo and Aquarium Research 4(1): 42–63.
  2. 2Divers S.J. & Comolli J.R. Metabolic and Endocrine Diseases of Reptiles. Merck Veterinary Manual (full review July 2025).
  3. 3Oonincx D.G.A.B. et al. (2020). The nocturnal leopard gecko (Eublepharis macularius) uses UVb radiation for vitamin D3 synthesis. Comparative Biochemistry and Physiology Part B 250: 110506.