I'd like to second the notion that Ancistrus can be a hazard to clutches of eggs. I too have an Ancistrus in a tank that I'm trying to breed apistos in. While I've never actually seen the Ancistrus eat any eggs, I'm highly suspicious. I've seen the Ancistrus slowly slink over to cocunut shells where it looks like apistos are guarding eggs. I even went as far as to put the Ancistrus in a floating container...and she climbed out of it during the night to get back into the main tank, which means that she braved the non-water world momentarily!! I'm finally able to make room to move her out of the apisto tank, so I'll keep you posted.