You know when you say the area of the head and dorsal fin has dipped, do you mean it looks sunken in.
Tumors
Symptoms:
Fishes with tumors have distended bodies or lumps on the skin. Unusual growths or swellings may occur in any part of the body. If they occur in internal organs they tend to cause firm, noticeable swelling to the general body shape. Tumors are usually confined to one area of the fish but they will continue to grow over time, weakening the fish until death occurs.
Cause:
A variety of environmental factors such as chemical pollution or severe viral infections. A predisposition to tumors may be inherited from a fish's parents.
Treatment:
There is no chemical remedy for this condition. Surgical removal of tumors can be attempted, but there is a high frequency of recurrence.
Tumors
Symptoms:
Fishes with tumors have distended bodies or lumps on the skin. Unusual growths or swellings may occur in any part of the body. If they occur in internal organs they tend to cause firm, noticeable swelling to the general body shape. Tumors are usually confined to one area of the fish but they will continue to grow over time, weakening the fish until death occurs.
Cause:
A variety of environmental factors such as chemical pollution or severe viral infections. A predisposition to tumors may be inherited from a fish's parents.
Treatment:
There is no chemical remedy for this condition. Surgical removal of tumors can be attempted, but there is a high frequency of recurrence.