When they get big they pinch off branches on their own and make new frags. I was flushing several down the toilet every week. Ones I kept, I would take the frag and poke a hole through the base with a toothpick and run fishing line through it and tie it to a piece of rubble. In a week or two, cut the line and pull it through the frag. As for toxins, I wouldnt worry about it.