well if it would be me I would stick with a slate or paper towel for a substrate. Bark is no good and sand is a pain in the kaboose. You should be able to sex them at 5 or six months old for sure. The males will get a triangle of pores down on their rear belly between the back legs, also will get bulges down by the anus. Best to find some pics of these to verify. Sorry I have no camera. I would not put any two together until you want them to breed. Males will fight to the death with each other. You don't wan't to breed a female till she is at least 10 months old and 50 grams minimum. Always maintain at least a 30 day quarantine period before introducing any new leos to your previous, 60 days is better. Good luck hope this helps some.
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Even if your on the right track you will get run over if you just sit there
20 leos,1.1 redtail boas,1.1 rainbow boas,1.1 cornsnakes, 1.0 tokay gecko,1.0 veiled cham, 5 dogs and a cat. Oh, can't forget Tater my parrotlet.