Thanks for writing this article. I was about to buy some BT for my water plants being ravaged by some type of caterpillar pests when i read your article and discovered that BT has the ability to kill fish. Not something I want to happen in my water garden. There are few things that can be used in the water garden due to inadvertantly killing fish or changing water quality. Neem oil has been recommended in articles by other authors on DavesGarden, and by my local aquatic landscaper. Do you have any other safe alternatives for use in aquatic gardens?