Any idea what this brown spot is on my bristlenose pleco’s back? It just kind of appeared about a week ago. It doesn’t appear to be getting any larger. Included an image from my macro lens. All other fish in tank healthy. He appeared to be scratching his back this morning. First time I’ve seen that happen.
80 degrees
0/0/20 (ammonia, nitrite, nitrates)
pH 7.2
kH 2, gH 10