Recently I have noticed that some of my fancy guppy's fins were torn, One of my neon tetras appears to have torn fins and very faint spots that don't appear to be ich. Another one of my guppies has been staying near the bottom of the tank and has white poop. Last weak I lost a pleco, he had a white spot on him that grew, I posted about it on the forum but nobody helped me until later. My water parameters are nitrite:0ppm, ammonia: 0ppm and nitrate is 0ppm. A few days ago I did 2 doses of erythromycin but I ran out. Please help.