I want to put some cichlids in with my diamondback turtle hatchling but I want something that is very fast as I don't want her having them as a meal. I will get some that are about her size so that hopefully will deter her from thinking of them as supper but I want something VERY fast.
The only thing that can deter a turtle from considering a fish a snack is size. Turtles will not make an attempt on fish much larger than themselves... But, the fish will think differently of the turtle.
The fastest swimming cichlid is whichever one I'm trying to catch. (Sorry, I know that's not helpful, I just couldn't resist)... I would agree with Dave that the cornering factor has a lot to do with how soon a small enough fish will be a snack, but they do 'sleep' so for a small enough fish it'll be a matter of time one way or another.
I've heard many cases where fish that shouldn't be kept together will co-exist for years and then one day the big fish eats the little fish. Just remember, it might work for a while, or just the first couple days.
I have 2 red ear sliders and will throw my misc cichlids and fry that are hybred's in the tank at times.
I recieved a bunch of albino's 8 males 3 females the males were actually full grown and larger than the turtles. When awake the males had no problem attacking the turtles and fighting for food right in front of them.
But When the lights go out things change. I once turn the light on in the other room and it must have been just enough to scare one of the turtles because he went to the surface, and he was carrying one of the males around in his mouth.
Now I am down to just 2 males in the turtle tank, and one male in my cichlid tank. The turtles have killed the rest and when they do it the fish just dissapears and then they don't eat for a week or so and then it happens again, always at night though.
Although now it is been a year and the turtles are larger and a lot lazier I think they have realized it is too much work to chase the fish so there is a few other fish that survive as well. But while the turtle is young chances of keeping the cichlid is pretty rare with my experiance.