Koi nipping at goldfish

[Ana]

I currently have a considerably big and deep pond, couldn't tell you how many gallons or litters it can take, but due to how big it is I've gotten 11 comets , and recently gotten 2 kois about the same size in the pond.
2 days ago I realized two comets were hanging out on top of the water surface together, almost cuddling from one end to the other. The next day, one of the comets were dead. I checked the corpse, there was no external wounds except a bruise on a fin. right then I realized someone was attacking the fish, so I waited and tried to find the other comet, and he had a missing fin. This comet is around 10cms (I don't know inches.. sorry) maybe more, and always had seen him as almost an alpha fish, is now afraid and constantly hiding in roots.
I found one of the kois, slowly nipping on a comets fin. they weren't chasing, or swimming away, just standing ztill and slowly got to him and kept nipping him. I would say thus is mating behavior or something, but I just recently gotten them theure like 10cms long, I don't think they're old enough for it.
I'm scratching my head to find an option, because I know I can't put kois in an aquarium, and I don't have an other place to isolate the kois into.
I don't know if their personality is just agressive, or if we did something wrong.

 

[j.w]

and welcome @Ana
Really not sure what is going on, sorry tho this is happening. Maybe test your water first to see if anything is off there.

 

[Ana]

View attachment 158108and welcome @Ana
Really not sure what is going on, sorry tho this is happening. Maybe test your water first to see if anything is off there.

sorry for the late message, but it's kind of embarrassing to admit that for how many years we've had this pond, we have never actually tested the water.
I'll have to talk to my brother as to where we can find a test kit.
At the moment I got 3 comets in a hospital tank, too small for them but for now thats all i have for them

If nothing comes from testing the water then I guess we'll have to find a different place for the carps

 

[GBBUDD]

That is not a large pond, one young koi is will fill that space in a few short years. stick with the comets or seeing as your in the tropics your choices are almost endless. a couple flower horns would be cool

 

[Lisak1]

I agree - I don't know for sure how many gallons you have but it it FAR too small for koi. (Not that this is the problem as koi and comets can live happily together in a pond.) I'd rehome or return the koi before you have a bigger problem on your hands.

 

[GBBUDD]

Actually I'd get those spitting fish. They spit as insects that are on branches over hanging the water. I see it now go walking by them and have them spit at yeah or your guest that would be comical. I had a clown trigger that use to snap his jaws as I walked by demanding a meal.

 

[Ana]

That is not a large pond, one young koi is will fill that space in a few short years. stick with the comets or seeing as your in the tropics your choices are almost endless. a couple flower horns would be cool

sticking to comets and shubunkin was the plan initially. I've separated the kois from them, and peace has been restored.
Though we in the past had a koi in the pond along with the goldfish, and he did get pretty big for what I remember, he was doing good! I think he might have still been alive and kicking today in there.

 

[Ana]

Actually I'd get those spitting fish. They spit as insects that are on branches over hanging the water. I see it now go walking by them and have them spit at yeah or your guest that would be comical. I had a clown trigger that use to snap his jaws as I walked by demanding a meal.

I've never seen a spitting fish, I don't think they sell those over here

 

[GBBUDD]

They are amazonian, but I have seen them in the past