I have a pond in my backyard about 13 x 8, its 1-2 ft deep around the edges and 2-3 ft deep in the middle. it has about 5 koi, apx 7-9", and 7 goldfish apx 5-7" a few weeks ago I realized one of the goldfish was missing an eye, no big deal, i hear about this all the time. today I look at the pond and see one of my goldfish just sitting there along the side of the pond looking like it had just gotten mauled by something. its fins were clipped and its face was messed up, missing most of an eye and was torn apart, as well as a section on its back. i looked at my other fish and saw another goldfish of the same apx size(6") that had the left side of its face ripped off, missing eye, no scales or anything on that side, ripped right down to the gills. it wasn't as messy as the other fish looked, looked like a clearcut. the fish was swimming around fine, just looked like it was in a horror movie. i removed these fish and stuck them in a 40g barrel and put anti fungal and stress coat in with them. the one that looked mauled is swimming around again and the other is continuing to swim about normally. I looked around the web for diseases and it doesn't look like anything I can find. it kind of looks like a crayfish grabbed them but I don't have crayfish in the pond let alone one big enough to grab them. there is also a rather large frog that hangs out in the pond from time to time, but i don't think a frog could inflict these wounds. also I keep about a 9" yellow bullhead in the pond. I raised this from about 1.5" and I know they can tend to be aggressive but I have never seen it act that way. It use to be in a tank with bass and would get bullied by them until i got rid of them, then by itself till about 7", then in the pond for the past year and a half. It has always minded its own business and has never even tried to go after the goldfish even the ones that were easily small enough to eat. any ideas what could be wrong with my fish?
^^^ Or bird.