Recently [4 days ago] I was given 3 very attractive +/- 4 inch Koi. I've
added them to my goldfish pond, and they seem to be acclimating well. I have
added Koi in the past [several years ago], but they've never survived. Since
they have generally just vanished, I've suspected they were gotten by a
heron. The only one I've found "floating" was definitely pierced by
something. I think I've discouraged the heron with a decoy I move around
from time to time since the goldfish don't seem to ever vanish, thank
goodness.

But my question is: are Koi and goldfish really compatible? I seem to recall
reading somewhere they can be competitive and belligerent to each other; but
I'm not sure if I actually read that, or misunderstood what I read, etc.

Any info welcome.

Mila