if i'm not mistaken, they fall into the iguana family. if he looks "skinny," don't panic...it may just be time to eat. if he looks emaciated and sickly, then there're problems.
i've never had one, but i believe that they like to have plenty of rocks and such to climb on.
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currently have:
snakes:
1.0 ball python (snake'n'bake)
1.0 reticulated python (mousetrap)
venomous:
1.0 pygmy rattlesnake (gordon)
0.1 mozambique spitting cobra (fluffy)
lizards:
1.0 nile monitor (dick)
0.0.1 egyptian painted agama (george)
0.0.1 blue tongue skink (skinky)
0.0.1 red sided skink (skinky jr.)
0.0.1 desert horned 'toad' (grinch)
fish:
0.0.6 red belly piranhas (milich, teo, sonya, kwanda, kasim & neclord)
mammals:
1.1 dachshunds (gus & heidi)
5.3 misc. cats (ho-hum, freak, pritchett, ghost, church, gypsy, flypsy, & hand)
1.0 child (michael).