Because Perry entered his lair through their pond, the O.W.C.A., to avoid lawsuits, made these unnamed Koi fish secret agents. Major Monogram didn't know how a tunnel got placed through the middle of a koi pond in the neighbor's backyard. The unnamed koi later came to Perry's rescue in Attack of the 50 Foot Sister, while he was trapped in a baby's high chair. When Dr. Doofenshmirtz was putting the stinking bottle of diaper smell into one of his inventions, the koi swooped in and got Perry out of the chair so he could save the day.