Fin rot or tear?
I just noticed a tear on my goldfish's tail. I can't tell if it's a fin rot or a small tear. There's also a small piece of his tail dangling near that "tear."
He's eating well and is very active and I do not know what could have made the tear. The only thing in my tank (80g) is a filter and two air pumps.
Temperature is around 60f
I also have 3 other goldfish living with him