When strolling down the reptile aisle, you will likely see a variety of different heat, daytime and nighttime bulbs. Take a closer look at the daylight bulbs and you may see a "UVB" rating on the packaging. Knowing what UVB is and how it works is vital for the health of your reptile. So, what is it? 

What is UVB?

Types of light are characterize by varying wavelengths expressed in manometers (nm). Ultraviolet B light (UVB) has a wavelength between 280 - 320 nm. Many reptiles synthesize vitamin D3 in their skin when exposed to this UVB light. Since most reptile species are unable to utilize dietary vitamin D3, a lack of can ultimately result in metabolic bone diseases in reptiles and amphibians. 

Metabolic Bone Disease 

Metabolic bone disease (or MBD) is a disease that can manifest in reptiles and amphibians from lack of vitamin D3 and calcium. Although you can purchase vitamin D3 (Pisces recommends: Repashy SuperCal), certain reptiles seem to be dependent on skin-manufactured Vitamin D3 . Reptiles and amphibians effected by MBD will pull calcium from their bones and replace it with fibrous tissue. This process causes growth deformities, as well as difficulties with locomotion and feeding. 

What Needs UVB?

We understand that most diurnal (daytime active) reptiles require UVB. This includes but not limited to: bearded dragons, collared lizards, uromastyx, veiled chameleons, desert skinks, milk snakes, carpet pythons and box turtles. Generally, nocturnal species of reptiles do not require light UVB, such as cave geckos and crested geckos. Amphibians are also able to utilize dietary vitamin D3. 


Humans have three different types of cones in our retina, each one being sensitive to different wavelengths. From these three types, we are able to make up our entire color spectrum. Unlike humans, Reptiles have a 4th cone that picks up emissions in the UVA portion of the electromagnetic spectrum. This will essentially ensure your reptile is not color blind. 

Bulb Choices 

 It is very important to make sure you are buying the proper bulb for your reptile. Pisces recommneds: Exo Terra Bulbs. Follow this basic guideline for choosing the right bulb for your reptile.

It is very important to replace your UVB bulbs regularly! Follow this chart to know when to replace your UVB bulb! 


UVB Index Radiometer

Here at Pisces we offer a Digital UV Index Radiometer service. Simply put down a deposit, and take home the handheld device for 48 hours. You can use this radiometer to test the UV light output of your bulbs and adjust your terrarium accordingly. Simply follow the chart on the top of the UV reader to ensure optimal UV lighting for your reptile! Click Here to watch an instructional video!