This happens once in a while on only one of my 4 red parrot cichlids (yes, the "man-made" ones). The black doesn't stay. Sometimes it's just a spot and others times its the whole end of the tail or dorsal fin.
25% I would say do a 50% 25% is not much for a parrot fish. and do a weekly water change.Thanks, I will check, although I just did a 25 % water change less than a week ago.
That's a huge pleco. I say stick to better water changes. 50% every week. that's to be sure your tank is clean. that pleco puts out a lot of waste55gal with 12 neons, 5 small catfish, 6 black skirt tetras, 6 zebra danios, 1 other red parrot and a 12-13 inch pleco. All the water parameters test fine. Everyone looks and acts as they have always done. I have had the pleco for about 5 years, the smaller fish (either the originals or their offspring) for 3 years. The red parrots are the newest being here about 6 months. I have had no major problems or illnesses.