Long story short I rescued this pleco about 2 years ago.. every fish I bought to go in tank dies it's so heart breaking to me I try and figure out what I'm doing wrong and I just dont get it..my pleco is declining I know hes sick It kills me everyday not knowing what I can do to help him. I lost my red tail shark just last evening and he was so big and I loved him so it shocked me when he was belly up still breathing then later that night he passed.. i only have one baby fish in there and my plenco..please help me what can i do and what disease does he have. I need answers please...water levels are good I just had it tested at petco 2 days ago. I did a 75% water change today.. but my plenco been sick for awhile. Please help