That looks like a bacterial issue with the koi in the window with a chunk out the tail. I have a bekko in my grow on tank with same behaviour, body shape and fin damage, so what's happening is it's a bacteria eating the fins and mucus. Im treating this with salt and erradik as it contains Malachite green, you need a treatment with this or formalin (copper based). Any pink or reddish areas on fins or body treat with methylene blue by spotting it on the infected area as its (Antibacterial) That's my go to for ulcers wounds. Methylene blue is normally a tropical/marine treatment so if you don't see it in pond department and it's normally a small bottle. Hope this helps
Cheers I’ll grab some. 😊😊
That looks like a bacterial issue with the koi in the window with a chunk out the tail. I have a bekko in my grow on tank with same behaviour, body shape and fin damage, so what's happening is it's a bacteria eating the fins and mucus. Im treating this with salt and erradik as it contains Malachite green, you need a treatment with this or formalin (copper based). Any pink or reddish areas on fins or body treat with methylene blue by spotting it on the infected area as its (Antibacterial) That's my go to for ulcers wounds. Methylene blue is normally a tropical/marine treatment so if you don't see it in pond department and it's normally a small bottle. Hope this helps