I do not think it is toxic? It has been in the tank for well over a year with no problems and I divided it before for my old Armatus and my snakeheads were in there for 4 months. My friend has had it in his tank with all types of fish and never a problem. All my params stay fine. I am getting ready to change it anyways but I think it is safe.
I also had it in a tank with braskish Green Spotted Puffers and they were fine.
I also had it in a tank with braskish Green Spotted Puffers and they were fine.