Becuase Agent P used their pond to enter his lair, the O.W.C.A., to avoid lawsuits, made them secret agents. They later came to Perry's rescue while he got trapped in a baby's high chair. When Heinz 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 ("Attack of the 50 Foot Sister").
- They are out of the water on most of their appearances.
- They are in Major Monogram's division. Major Monogram didn't know how a tunnel got placed through the middle of a koi pond in the neighbor's backyard.
- "Attack of the 50 Foot Sister" (First appearance)
- "La Candace-Cabra" (Yellow koi)
- "Phineas and Ferb Save Summer" (Orange koi)
- Where's My Summer? (Agent File)