Hi,
Let me introduce my tank first. I got a 38 gallon tank and inside I got 1 Oranda, 2 Fantail, 1 Black Goldfish (don't know the breed. Forgot to check when I bought) and 10 neon Tetras.
Since last Sunday, I noticed that my Black Goldfish had 2 white spots on his side. As of Friday, it became...