It is quite possible that the black spot is part of the fishes colouration. Goldfish often have many different colours in many different shapes and shades anywhere on their bodies or fins.
It is quite possible that the black spot is part of the fishes colouration. Goldfish often have many different colours in many different shapes and shades anywhere on their bodies or fins.
I can only guess that the fish has an abscess. This is usually caused by poor water conditions. If you stick to the basic rules of fishkeeping the abscess may go away. The basic rules are :- 1 inch...
If a sebaceous gland duct is blocked by accumulated sebum, a whithead apears on the skin surface. If the material oxidizes and dries, it darkens to form a blackhead.