This web site (from a croquet club, I think) lists chemicals which can potentially be used to kill worms: http://www.oxfordcroquet.com/care/worms/index.asp#_Toc117517077 Two chemicals - anhydrous ammonia fertilisers and nicotine - also show up in this list of chemicals toxic to fish: http://www.fao.org/DOCREP/003/B0465E/B0465E05.HTM Michele