We have tried to have red eared sliders in with our gators. They wont last till the next day, and they have a lot of room. The gators are 9-10 feet though.
We had a very big slider in with our biggest black caiman 13,5 feet. it lasted a week. The slider was sort of a test turtle, to see if the caiman saw it as food. The plan was to keep podocnemis expansa with the black caimans, we have dropped that plan

Jonas