In the past, my turtles have always waged war on the feeder fish when they were added, but any that survived the initial massacre were safe from there on out.
I had a couple guppies that lived in with my turtles for a long time, even had some babies.
You also have to look at the species of turtles.
My muddies and stinkpots prefer dead prey, as they are not agile swimmers and give up pretty quickly, so they are pretty fish safe, providing you give the fish small nooks and crannies to hide in.
I probably wouldn't do a goldfish with turtles, but some of the smaller, agile fish like neon tetras may be fine.
Also, goldfish and turtles have different temperature requirements.