why has my goldfish started to change color, it was gold and white and now getting black on its fins, belly and tail. It is not a young fish I.ve had him about 5 years and he is about 6in long none of the other fish seem to be changing.
Ours did the opposite, he had black bits on his tail and fins, then about 2 weeks after having him they disappeared, no idea why, but he's still ok now!
Thankyou for your help. Dont know what it was but he has gone back to his normal colour apart from a bit of black on his tail, and seems to be very healthy.