Some fish eat it. I feed it to my koi and goldfish. I had lake malawi cichlids that would pick at it too. Like any plant, it will flourish or not depending on your water conditions. The leaves don't really grow. They are tiny and each plant has about three tiny leaves. My theory is, if your water is pristine, no excess phosphates or nitrates, then it hampers growth or slows it down considerably. I've had it do extremely well in some tanks and not in others. It has the potential though to be problematic, clogging filters and such makes it a nuisance. That and the fact that once you have it, it seems impossible to get rid of. Even one tiny leaf will start a new colony. But, on the other side, it's great cover for fish as well as great nutrient export.