About 15 years ago I used this stuff in a 120 gallon tank, with lots of T8 bulbs to light it, but no fertilizing to speak of, and very inadequate CO2. Vals grew spectacularly as did sword plants. I had several cories in the tank, but they all died, one by one. When I looked at the dead ones, none had barbels left. Studying the last survivor in the tank I also noted that it had no barbels and was not eating. All of these deaths occurred within a few weeks of adding them to the tank. My conclusion was that the sharp grains of the substrate were damaging the barbels. That conclusion was helped along by the many small cuts I got on my hands and fingers when I was planting the tank, and each time I replanted it. I really liked the look of the substrate, but I haven't used it again because of the effect on cories. All other fish lived full lives in the tank with no problems, including loaches.