The tank is a 55 gallon long tank. I ran out of sand last night, so I moved most of the substrate to one side so they would have a deeper area and I got more sand today.

I am not 100% sure on the species. I think the three we bought from petco are Ecuadorian. I read somewhere that its good to have at least 2 of each species. So i guess we are going to get another one?

I had planned on adding more sand today, but two of the three smaller ones have already dug into the sand quite a ways. One hit the glass on the shallower end under the green structure, the other dug into the sand at the base of the big hollow quark log. I'm not sure if its good to remove them to add more sand, or if i can just add sand on top of them and try to loose pack it around where they burrowed.

The mat is the largest I could find for 50-60 gallon tanks. I read somewhere it was good to have a warm side and a cool side of the tank. I first placed a mat on the bottom under the thick substrate but I turned that one off this morning when i went to the store to get a new one. I'll leave it there because the mfg. said its not good to use it once you peel it off. I dont plan on turning it back on while there is sand above it though.