It's normal. Mine dose it. I think if you check some of the other threads the vedict is out on how much is the real question. On one posting the pic of the water that was posted made it look like the fish had been through a blender. Some say to much means an unhealthy fish or bad water quality. My lion sheds but not so as to make the water full of skin or unsightly. My water is great except for an on going battle with high nitrate. I think it's all about how fast they are growing, but I am no expert!