Yes, they will rarely come and "feed" witht he others in the tank. They instead poke around at what floats to the bottom.
The only exception is frozen bloodworms, they will try and get these but it seem thier eyesight is poor and they try and find them by smell. Which means the other fish have often eaten all the worms by the time they even bother looking for them.
Mine actually eat a lot of ghost shrimp. You might try buying a dozen of the smaller ones and putting them in there. You will probably lose one every couple days. These loaches also seem to like dried shrimp pellets (catfish pellets).