If I buy koi for our pond from a pet shop at this time of year will they servive and grow by spring? I live in zone 6 so the water is cold now and the pond will freeze very soon. The reason I ask is because seven nice koi dissapeared from our pond. We had a net over the pond to keep the leaves out so how did the koi disapear? Ten gold fish were not taken. Maybe they were koinapped. Don't know. Any way need to replace the them.