A common mistake is cohabitation (if sharing tank or can see another beardie) , even if he can see another beardie , or a snake or very large lizard ?
Are there other pets (cats, dogs ) in the household ?
And details of your feeding schedule and other husbandry aspects .
Might be a very easy fix .
Photos of the tank and showing substrate and lighting and of the beardies will help too. Use XIMG button to upload photos from your computer.
How heavy are each of the beardies ?
...... recommend weighing them regularly (weekly say)?
Another common mistake is to believe based on bad advise (often given by a petshop or incompetent breeder or by a previous keeper who is incompetent) that you have the heat and setup and UV correct. More often than not the Noob beardie owner has many problems simply because he took the bad advise and knew no better .
Can you give us a good rundown on the setup and schedules (light and feeding) :
Basking light
........ is it a coloured globe ? (BAD)
........ what is it's wattage ?
........ how far from the basking spot ?
TEMPERATURES ?
>>> daytime
.......warm zone
.......basking spot
...... how are you measuring your temperatures ?
TOO COLD = SLEEPY DRAGON
>>> overnight minimum viv temperatures ?
UVA AND UVB ADEQUATE ?
>>> is the uv rated AT LEAST 10%UVB ?
>>> is it a COMPACT (curly globe & WATTAGE ?
>>> or a T8 tube ?
>>> or a T5 tube ?
>>> or an MVB ?
VERY IMPORTANT : what is the brand ?
(not all UVB compacts and tubes are created equal or as well , many shops sell their own brand (Zilla, All Living Things, Reptile-One, Nat Geo , Natural Selections (in green boxes) which are cheap Chinese clones made very cheaply using very poor quality quartz glass and cheap phosphors ==> very poor UV spectrum produced incl UVC band and bad parts of the UVB band)
>>> also is it covered (in a domestic fluorescent light fitting )? == BAD
>>> also is it sitting ontop a mesh top ? == BAD
>>> how far from basking spot ?
too far and the UVA and UVB WILL BE TOO DILUTE.
UVA FLUX TOO LOW where dragon is ==> a very lethargic dragon w/ a very poor apetite just in the short term , and neurological problems if this persists , not to mention MVB if UVB flux too low long enough with inadequate metabolisation of dietary calcium or inadequate intake out calcium
http://www.arcadia-reptile.com/wp-content/uploads/2012/04/guide-bearded-dragon.jpg
TANK
>>> size (L x W x H) and construction , photos of the setup are often helpful .
SUBSTRATE ?
>>> is it sand ? == BAD AND IF CALCISAND this is EXTREMELY BAD/LETHAL when ingested
>>> is it particulate ? == BAD
SHARING TANK ? == BAD
TOO SHORT A PHOTOPERIOD (lights are not kept on long enough each day , will make beardie think it is winter , recommend at least 14 HRS PER DAY)
FEEDING SCHEDULE (I recommend at least 2 hrs lights/heat on before first live feed and after last feed of the day)
>>> when are you offering live feeder insects ? what are they ? how big are they ?
>>> when are you offering greens and other veg ? what are you offering ?
good guide is here :
http://www.beautifuldragons.com/Nutritionframeset.html