from the second pic looks like it just has a prominent underbite and the color is gone from bumping into things (like a fishy callus-the bumping wore the scales off and hence the whitish/ lack of color. does the guy swim erratically ever against the glass? what sort of substrate/ornaments do you have (maybe poking around in them too much caused the scales to wear off). i do not think it is anything to worry about if behaving and eating normally (and having full range of use of its mouth). keep an eye out for any change for the worse. i have a feel, as ColinT that it is from contacting surfaces and the scales just wore off(and formed a thicker part which sticks out a bit, much like a callus).
cheers