Hi all,
This is more of a goldfish question than a koi question - I hope that's ok. We recently completed our pond a few months ago and in August added 2 koi and 4 goldfish (3 smallish comets and 1 large fantail). We have noticed the comets and fantail tend to stay close together but over the past day saw two of the comets completely harassing the large fantail, chasing it around the pond and nudging aggressively at its flanks. I tried to bat them away but they would not be deterred. The fantail is getting pushed into very shallow water on top of the marginal plants and I'm afraid it will jump out of the pond or get stuck. Is this mating behavior? Should we separate the fantail? The koi and the remaining comet leave the fantail alone.
Everyone seems to be healthy, I have seen no damage on any of the fish.
Any advice appreciated! Thanks.