we are talking gold fish here. I just bought two blue orandas, about 6cm long. I put them in the tank and the next morning and I found chasing behind my other fish, which is a cross of fantail + oranda, probably 4x its size and snipping/eating the tail. I have now separated all of the younger fish into another tank.....
I have 4 big fish, probably around 20cm long, and all of their tails are damaged with filled with blood streaks...
Is this a sign of breeding or something else?