The subject of hydra appears about once every 4-5 months. I found an interesting article onthe subject in the October issue of Aquarium Frontiers. The URL is: http://www.aquariumfrontiers.com/1997/oct/product/index.htm The article reports on a highly effective drug called Panacur in the US, Flubenol in Germany, that kills hydra while leaving plants AND killie fry healthy. It's a drug that you can obtain through a veterinarian. Bill Vannerson McHenry, IL USA http://ourworld.compuserve.com/homepages/William_Vannerson (updated 9/25/97)