I went away for two days and I came home to a sick fishy. He seems to have a bit of fin/tail rot, although its not too severe. What problems me most is the redness of him. He is usually all orange. When I saw him he is really red behind his gills. I have medicine that I have been treating him with but I can't tell if its gill disease or septicemia. The redness is kind of all over to about mid-drift of his body. He's eating okay but I put him in a hospital tank and he doesn't like being alone. I gave him I believe Maracyn or Maracyn 2. I'm at work so I can't look at the box. It says it treats all of those diseases. I'm baffled as to what happened! He's eating okay but he looks really bad. Could the temperature of the water be at fault? It's been really hot and his water has been going up to the upper 70s. There is another little goldfish that swims in the same tank, and he is fine. I'm not really sure what happened, I just really hope he gets better.