Question
I live in New Jersey and have a wisky barrel pond,with 2 koi,water lilly and iris plants in it. Do I have to bring them in for the winter?

Answer
I assume the barrel is only about 20 gallons?  I also assume the koi are just babies?  Koi grow to 2 or 3 feet long.  The koi experts say to have 1000 gallons for the first koi and at least 100 gallons for each additional koi.  I'm telling you so you can plan to either build a huge pond or find them another pond.

Yes, you should bring them inside for the winter.  A whisky barrel is all above ground normally and small enough that it will pretty much freeze solid, killing the fish and lily.  Some iris though can freeze solid.

You can use the same pond indoors in the basement or a garage.  You could also use an aquarium or Rubbermaid livestock tank for the koi (the bigger the better).  If it's below 50 degrees F, you don't need to feed the koi.  I keep a 20 gallon tub pond in the basement.  I've never had koi in there but have had baby goldfish and now I have a betta in there (all by himself).  The water lilies and iris can be overwintered warm and active or in a dormant state.  See http://www.fishpondinfo.com/plants/overwinter.htm for more on that.

Good luck!