A common mistake that goldfish owners make which is quite easily done is treating their fish for ich when in fact it’s breeding tubercles. Proper diagnosis in identifying diseases can save you time, money, and eliminate stress on fish. These breeding tubercles that you see appear like pimples on the gill plates. Lots of people mistaken this for ich when in fact it’s not.
Male goldfish develop these breeding tubercles several times throughout the year. This symbolizes that the goldfish are ready to breed. A good way to tell whether it’s ich or breeding tubercles is to observe the rest of the body. If the white spots or pimples are only on the the gill plates then they are breeding tubercles. If there are spots elsewhere that appear on your fish then you have ich. If it turns out to be ich then I would suggest getting ready to start treating your goldfish for whitespot disease.