My managuense does the same thing. she's by herself and lays eggs about every 2-3 weeks now. She will act super territorial and not eat for about 5 days or so and then give up on the eggs and my pleco will suck the eggs up, she won't eat them. After this time your fish will hit a feeding frenzy to replenish, she'll be really mal-nurished and kind of pale so treat her to a feast. The water also gets really out of balance during this time from all the biochemicals your fish has secreted so it's also important to time your water cycling around this. Do a 10-20% water change and chemical balance after she's given up on her eggs and make sure you check your filter status. This is a really entertaining time tho, your fish will get really aggressive and do cool things. As it matures, during this time you can play with it near the glass. I've found that if you feed too often and the water is around 80 degrees she will lay eggs more often, but if she's laying eggs that means she's happy and you are doing a good job!!
