hi,
i have a turtle/fish set up and things work out fine(most of the time). i have a 5inch painted turtle cohabitating with three otos, four peppered cories a khuli loach and a few feeder fish. Honestly, it can be done, but expect to lose the fish that aren't "turtle savy". you also need to have a set-up that maximizes the fish's chance for escape. For example, my turtle's basking area is constructed from bricks and slate with little openings that the turtle can not get through. if the fishes are feeling threatened by her, they dart under the basking area where she can not get them. i have lost a few fish (do NOT grow attached to them if you want to try this set-up). she is particularly fond of eating the otos when she can catch them. it seems as though once one fish gets attacked by the turtle, the others become smarter, as in stay away from her. most of my losses were in the early stages of fish intro and i have not lost any fish in a while. i have never seen her go for a cory or noticed any nips to them. guppies are a great idea cecasue they breed like mad and turtles really should be given live food as this is their natural instinct to eat such food (not floating sticks all the time).IME, neons were a terrible mistake as she made short work of them! bottom line, if you have a hideout for the fish, they will soon outwit the slow moving turtle, but be prepared for some losses.
regards!