Why koi ‘do what they do’??

My second favorite subject after genetics of the clan Nishikigoi is – why do koi do what they do?

So I’m going to ask some questions and see if you know the answer:

1) A few koi are seen ‘mouthing’ the pond surface near the walls. But no food is visible, what are they doing??

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

3) Koi are entering the autumn season and all of the sudden the shiro Utsuri are looking better than ever! Why?

4) A koi is rubbing against one particular pipe in the pond. Over and over it swims to the pipe and pushes it body against the pipe. Why?

5) A new koi is introduced to the pond and the fish swim after it and seem to be most interesting in the new comer. Why?

6) A fish is anesthetized and when returned to the pond, all its pond mates follow it as if in a ritual. Why?

7) A koi looks like it is ‘chewing’ but no food has been added. Why?

8) A koi gets ‘cloudy’ as if a film is on its body. What does this mean?

9) A koi blows bubbles as it goes to the bottom of a deep pond. What does that mean?

10) You wake up and go out to feed your koi. The pond is covered with ‘suds’ and the fish are all at the surface gasping for air. What happened??

JR