>>Is there a food that fattens up a leo's tail better than others? Do mealworms fatten them up more than crickets? Vice versa? Also, I currently have my 5 month old leo on washed playsand as the substrate. I know a bearded dragon needs to be about 10 inches before it's safe on playsand...what about a leo? My leo is pretty good size for a 5 month old. I don't know his current mass, but he is pretty big for his age. Is this age leo ok on playsand? Thanks for any info in advance. ~Eric M
I think a mealworm might be a little bit more fattening and includes some of the same nutritional value - but then again, it's how you gutload your feeders. If you gutload them really well, they'll be more nutritious for your leo
Also, if you're using a corn-based food for your crix, be sure to not get them moist in a humid area because i hear it causes some problems... infections to your leo and whatnot.
Also, at this age, you may not want to use sand because it can cause impaction to your leo - if he dives for the crix, he can get a mouthful... same goes with an escaped mealie during the night (unless it buries itself into the sand and wanders around in it). I hear it's better to use sand when you have older leos... but the best substrate for both would most likely be paper towels, slate, tile, etc. because there's no risk of impaction. if you use sand because you want a naturalistic looking tank, slate is best because leos come from rocky areas. But, if you still want the look of dirt and sand... you can use brown paper towels
that's what i use! i just went to work one day and took a couple of those big brown paper towel rolls from the bathroom - of course, with the approval of the ever-so-kind janitor - she's cool 
anyways, i hope i helped out some
good luck to you and your leo! take care 
[aimee]
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1.0 Albino Leopard Gecko (Melvin)
1.0 Black Lab / Pitbull mix (Mikey)
1.0 Blue Fighting Fish (Blue Balls)
2.0 Fire-Bellied Toads (Norman & Forman)
http://aimee.i8.com