I was sitting just watching my fish today, as I like to do, and noticed some new behavior. I have 16 guppies that I started out with to make sure I would not kill my tilapia when I bought them. A week and a half later I added 30 blue tilapia. From that time they have co-mingled nicely. 4 of my tilapia died and I squashed one trying to catch it, I banned myself from the net for a week. So today I notice all the guppies congregating in the corner in what appears to be a defensive pack. Is this a sign that the tilapia are of the age to become more aggressive and they will soon be having guppy for dinner?