uromastix

Question
i have 2 mali uro's in a big 55 gal tank they have a large basking rock with a "plant light" high uvbs and heat good bulb. but my question is, why does the large male all the sudden just sleep in the basking spot until i turn the light off he is a gentle uro never bites but sometimes snaps at me and i also belive i have a female male mimic uro i thin khse is brumating she hides in the den and sleeps all day and night comes out and eats when i am not looking every few days can you shed ne light on this subject?

Answer
 If you are in the Northern US, Canada, or northern areas of Europe, both uros are in two forms of brumation.  You male is doing the "branch potato" version and does not want to be disturbed from the best basking spot in the habitat.  The female may be doing a yo-yo version, or if what you have is a sneaker male, he will want to hide from the alpha male and save himself from being attacked.
 Unless you have a vet check to assure you of the proper sex of the female, you may want to get another set-up.  Like many lizards, uros are territorial and don't want to share habitat.