I have several species of pygmy cory as well as a false cory (Aspidoras) in a Flourite tank. They have been doing fine for the past 1.5 years. All the reports I have heard from other planted tank folks are that corys do not have any problems caused by Flourite. Cathy Hartland Middletown, MD http://www.nfis.com/~hartland/aqua/aquaria.html