Looking for free advice again

I was buying dog-food at one of our few LFS (hey its a small town)
and they had "peppered loaches for sale (~2.5"). I think they were
Lepidocephalichthys berdmorei or something similair. Do they need
to have a sand substrate? Or would a very heavily planted tank
(lots of places to hide) with gravel work? They had several for sale,
and I have room for a group of 5 or so (75gal tank)...
The other bottom dwellers in the tank that I'm considering them for
are black khuli loaches (Pangio oblonga???), juli cories and sids.
Good idea or not?
Thanx
Batch