I have Unipac "Black Glass" gravel in my tank, which is 2-3mm. It doesn't feel sharp to touch. Unipac Black Micro Gravel 12.5kg [PAGI12A] - £21.99 : Tropical Aquarium / Fish Tank Plants for Sale, CO2 Sets, Fertilisers, and more Aqua Essentials, The Planted Aquarium Specialists I'm considering a school of panda cories. Would they be happy on this? Thanks!