Goldfish loosing fins

[giuliano]

I have a 55G aquarium with goldfishes only, the values of the water are OK, one goldfish since today is getting his fins severely damaged like if the other fishes are eating them , I wonder what this could be and if there is a way to help him regrow the damaged fins, thank you

 

[Zagz]

Exact parameters would be helpful. Did you witness any chasing from the other fish? When was your last water change? Depending on the cause the fins most certainly can grow back. Any pictures?