2) In winter a koi is moving at the surface as the pond, swimming as if they are hypnotized. What is it doing??

Koi are cold blooded animals. And in temperatures below 46 F they loose control of balance. In fact, I recall in a winter trip to my friend's koi shop seeing a vivid illustration of this. This dealer has a massive modern koi shop and outside the shop is a large but shallow pool that holds some production fish. In that pond were a hundred shusui. It was a cold and windy day and I'd estimate that the temperature as in the high 30s to low 40s. But the wind chill made it feel a LOT colder. I walked up to the pond and ALL the fish were on their sides! I thought they were dying! The breeder just smiled and said in a heavy accent-- " just sleeping!"

Another important physiological fact is that koi that are in good condition entering winter will , as a response to colder water, begin to shift what muscles it uses as water cools. Nature is amazing. And cold blooded creatures have a tactical strategy to survive. Nature is also very practical and logic prevails-- if a block of muscles is designed to make a fish swim fast in quick bursts, it is great for escape. And when a fish wants to move fast it can uses these muscles along with the slower muscles. But in winter expensive muscle movement ( expensive being any muscle that requires a lot of energy at a time of year when energy must be preserved) is to be shut down. So the cold effect AND the physiological 'choice' to not employ certain muscel blocks all works to help the fish survive the winter. Movement is to be minimal and when necessary, slower, muscle mass can be used-- muscle that requires less energy " more miles to the gallon" so to speak. This does create however an odd wagging motion and not a lot of speed. Again a perfect harmony of limited movement due to cold and need to conserve.

So once again, study your koi, look for other symptoms that will give a better idea of normal vs abnormal condition/movement.

Is there a film on the koi?

Is the koi red or streaked with red veins?

Are the other koi doing the same thing or are they all resting on the bottom?

Are the fishes fins clamped or ragged?

These answers will all help to assess if the fish is trouble or just wandering and looking for the sun or away from a cold current.

JR