Good question Walker! Wish I had a definitive answer for the first. I have read posts (a rant...I think it was feedback on aquabid actually) about someone selling the person plants that killed their fish! Fast forward to my recent receiving of some Limnophila hippuroides or L. aromatica. It produced a few side shoots so I broke them off to re-plant and noticed this stuff has a very pungent odor! I later went back to the tank to give the shrimp their evening snack and they're all doing laps around the tank!!! I had never seen it before. One would temporarily settle on the bottom and then "skitter" around and start swimming again. After one 50% water change they were still "freaking out", after the second, they seem to settle down some. I did another the following morning just to be safe. Some shrimp sites have postings about crypts or anubias being toxic (if you were to break a leaf off) but I have done both plenty of times without any signs of stress.
Inverts dying due to ferts in unlikely. I have read, some metals (like copper) can accumulate in shrimp and result in lethal doses over time. This would result in older ones dying "for no apparent reason". Again, this is from online "research" and I have no real proof to these claims. I dose plantex csm+b regularly and have healthy shrimp populations.
Don't know if any of this helps, but I didn't want you left :hang:
