Help! I've got 2 rope fishes in my 90 litre tank, water levels seem to be fine but suddenly one of my ropes have got an red pimple on her head near her fins. I'm really worried if something's attacked her because after I cleaned the tank my 2 ropes became aggressive with each other. Before they were the best of buds but now I almost never see them together again! Is there a way to solve this?? I don't want to loose my rope to a pimple. I feed them freeze dried tubiflex worms and they were fine with that, my rope with the pimple is fine and I just noticed it at around 4:00PM so please help ASAP!