Koi gasping at the top of the bowl! Help!?

One of my koi is gasping at the top of the bowl! It is a big bowl, about 3 gallons, and has 2 koi in it, and 1 fantail. My black and orange koi is gasping at the surface! The others look fine. Will it be ok in a 30 gallon with 2 clown knives? will that help it? The pet store guy said they'd be ok in the bowl...