Thread: I think my fish is dying

Well a dirty filter is my first guess, in which case changing his water could have done more harm than good. Often ammonia can build in the water and cause the symptoms that you just mentioned.

After thinking it through, logic led me to believe that it could also be a water temperature issue. With Fall rolling in it's very easy to let the water temp dip a few degrees, which would also cause the same symptoms.

If it's not one of those things I don't know what to tell you.