I just got done feeding the fish in my long 20 gallon tank and noticed a fake plant that was in the back towards the output of the filter and noticed a small red stain on a small part of the plant. My theory is that when my pleco was climbing the output of the filter and sliding back down that maybe he cut himself while he was sliding down and bled on it. My other theory is that I noticed since I added new black tetras to the tank to make the stockings 4 long finned and 4 regular black tetras and the pleco I noticed that almost all the tetras fins have been nipped at (pecking order I believe to re establish who is the alpha fish) Could the "blood" be from the pleco or the tetras, oh and the pleco has no cuts or injurys on him that I can see on his body when he is on the front of the glass or when he is laying on the bottom.