Will a full grown koi eat your red eared slidder turtle or will the koi?

A full grown koi will not usually attempt to eat an adult red eared slider turtle, nor attempt to consume a hatchling or juvenile slider in a pond that offers ample food sources for the fish and turtle. However, it it quite uncommon for turtles of similar size, including red eared sliders, to attack and consume young and/or injured koi within the small confines of a typical aquarium