CichlidFish.com - Fish That Think.

i have 2 oscars and and a pleco in a 70 gallon tank. the red oscar(12", i've had him/her? for 2.5 years) and the tiger oscar(8", 1yr 8 months) have been getting along really well lately, and have produced 2 sets of eggs. the 1st set was a month ago, i read as much info i could on behavoir. everything seemed fine. both fish were watching over the eggs. but they never hatched. i suspect the pleco ate them at night or caused enough stress that the o's couldn't do thier thing. well, i now have another batch of eggs, and the parents are behaving the same as before. what i wonder is if separating the tank would be good enough? do i need to remove the pleco(by the way he is 9"long) from the tank completely? he is essential to keeping the tank environment stable. but i do want babies. another thing i questioned is, would the female lay eggs even if the male wasn't fertile yet(assuming the red is female, and the eggs never hatched because of this). the red is hovering over the eggs most of the time, and seems to take on motherly insticnts. but i'm not sure. any help or advice would be greatly appreciated...thanks