I have had the best luck with my L129s (and L400s, and L450s) leaving the fry with the dad. Many times the new dads will eat the eggs. Sometimes it may take him a couple of times to get it right, but he will. All but 1 of my pleco breeding colonies are in bare bottom tanks. And if you find a fry or more, out of the cave with the egg sac still attached, you may want to take a turkey baster and try and gently put them back in the cave. You don't have to worry about feeding the fry until their egg sac is gone. Good luck.