I keep fish with mud and musk turtles in a large stock tank and I haven't had a single loss. Of course they're well fed and most of the fish are fast (minus the pleco).
The key thing there is it is they're babies not adults. Wait until they become adults and you will probably have chunks missing from your koi. I would deffinately keep an eye on them.visionaryrevolt;3484688; said:i got some 2 baby red ear slider with some koi fish, its possible not impossible