Black Kuhli Loaches

Question
Hi Tina,
It's Cameron again I decided to get black kuhli loaches instead of catfish so now I have two of them living with the honey gourami,two swordtails,two silver lyretail mollies and my mystery snail in the 20 gallon tank. I bought a fairly sized cave for them to hide in and they have made burrows underneath the caves walls like little pockets. Anyway my question here is that I've noticed that when I first put them in they had a hard time trying to dig into the gravel,and I know that I'm supposed to have a somewhat sandy substrate but i couldn't find a good source,is that okay that they can't easily burrow into the ground as long as they have the cave to hide in?
         Thanks again Cameron ;)

Answer
Cameron, I love these guys. I would still recommend a couple Cory catfish. They get along well and do not get large. They will share the cave fine. The Khuli's won't keep tank clean like a catfish. Medium gravel they can dig in easily but, as long as they have a cave that is fine. They are more nocturnal anyway. Your tank is stocked perfectly after the Cory's. Do not add anymore fish and you should have a great well balanced tank. Good Luck, Tina