Possible fish sickness on danio and plico, please help.

My lepord danio has just started to show possible signes of disease. He
has developed a lighter band that travels around the mid of his body.
He also has several large spots on his skin that are also lightened. It
doesn't seem like ich from what I have read about it. Also, this fish
has had clamped fins since I got him, but now that these spots have
appeared he is acting like all of the other fish and no longer clamps
his fins. Is he sick, or could he be changing colors in response to
food or climate?

Along the same lines my bristle-nose plico has also developed several
large spots on his back that are the same color as his normal speckled
colors. These have made it even harder to find him in my tank, since
now he blends in almost perfectly to the rock I have in there. The rock
is one of his favorite places to hang out on, especially during the
day. He is still fairly new, so I can't remember if these patches were
always there, or just showed up since I've gotten him. Any advice would
be welcome. My tank is 20-gal with 0 ammonia, 0 nitrite, 0 nitrate, a
steady ph of 7.6 and a fairly steady temp of 78F. None of the other
fish seem to be any different than they have always been. Thank you for
the help.

Sincerely,
Travis