I don't think it is toxins per se, but just more of an organic overload when they release their gametes, ie, "going sexual" It is just a form of reproduction that takes please and in our tanks, which are closed systems, the filtration generally is not able to handle it all. Ozman, if your fuge is lit 24/7 and you prune it regularly, then you shuld have no problem at all. Most problems with this is when a little bit gets into the display tank, if it gets ahold and starts growing, it may be hard to remove, ...