ok i got some mts the other day. and, they barely ever go into the sand like they are supposed to. they poop alot. everything is covered in their poop. but what really pissed me off was when they decided to eat the endler i put in that tank. i found him shreaded, barely even recognisable. so i caught my koolie loach from my other tank and put it in there, in hopes that he will eat them. its a sand bottom tank, thats why i got the mts. but are they really neccessary?