That thing under the bigger knife's jaw has been back again for a couple of months now. Does anyone know what it is, what causes it?For a while in the 4500 gal, the older knife had something underneath its mouth / gills, like a protrusion, bone / cartilage or skin, IDK, and I thought its some injury from trying to swallow too big a piece of herring or too bony a piece. It has been slowly diminishing and almost gone now but I had thought it'd never go away. If someone could explain what this could have been, we'd appreciate it.