there's a yellow watchman goby at the lfs with whitish discolorations on his skin, pinhead size lumps (they actually look like pinheads, under the skin) that are the same color of the fish on his body near his tail and near and on his fins on the side of his body, skin and fins had a ragged...
i fed mine pellets and they reproduced a lot. mine came in on a live rock. they're really cool to watch. i killed all of mine when i rinsed all my rocks in tapwater though.
i have a small yellow or gold one. even he will try to grab anything that comes near him. luckily he is slow and not as big. i do want to get rid of him though.