Scooter, I agree with you, If it was a fish that had been in the pond for a while and started swimming in and out of the skimmer it would be one thing but a shy butterfly that has just been introduced would concern me also. Is it the only koi in the pond? They seem to get more comfortable when there are other koi present, and they can be standard or butterfly or even large comets and shubunkins, just fish to swim with. the larger koi get the more they will wonder off from the school, but as young they feel more comfortable in groups. I'll think on this some and see if i can think of something else but in the mean time keep an eye on it, The skimmer can cause damage and stress the fish so be sure it's staying healthy watch the fins for blood streaks and fungus, and watch and see if he can leave on his own, if not maybe reduce the water flow rate going thru the skimmer for a short period of time or find a something that the water can pass thru but the fish can't to put over the skimmer door, Ex. Egg crating like what they use in DYI filters???