Funadvice Logo

Why is my fantail goldfish turning red?

Home More advice Pets & Animals

We have two fantail goldfishes, yesterday we noticed that it's tail had a streak of red. We got worried so we changed the water, in case it was a bacterial infection. I woke up this morning and checked the fish, now the whole tail is almost red and it's fins are turning red too. And I noticed one of the Oranda goldfishes were chasing it occasionally and nipping at it. I'm so scared for it, it runs away from it, but I'm afraid that it'd injured and it can't run away quick enough. Why is it turning red? Should I be worried? What should I do?