I am very new to looking after fish, and I got my first fishes 2-3 weeks ago. I only have 2 fish, one is a yellow goldfish, and the other is a shubunkin. A couple of days ago my shubunkin began to act very oddly, such as staying nearer to the top of the tank and not moving very much. He does still sometimes swim quickly, so he has not lost the ability to do so. Today I have noticed that his top fin is no longer the way it was when i first got him. The fin is very short and red. I really need help on finding out what is wrong with him as I am really worried. His other fins are also different from the first picture, but the top is the most drastic. I have attached a before and after picture to help. Please let me know if it is damaged, completely missing or if this is a sign he is sick. I am scared that the yellow goldfish he shares the tank with could have done this.
Thankyou very much!
Thankyou very much!