redearslider.com

Hi there. I've got a weird question for you all. My turtle's an adult male RES, about seven inches long, and somewhat shy/skittish. I keep the tank at about 76-78 degrees (basking area hotter obviously) and a neutral pH. My classmate was doing a research project involving crayfish, and I've grown somewhat attached to one of the males— who incidentally is missing a claw (don't ask me how, he arrived like that) and I'd like to adopt him after the research is done. However, I know crayfish can be somewhat aggressive— I was wondering if it could hurt my turtle or vice versa. My turtle never eats live food, so hopefully wouldn't try to eat him.

I would use search box top right for lots of threads on crayfish and turtles.

Note some freshwater crayfish has a short life expectancy , no more than 2 years.
When molted will become more of a target for your turtle.
Regular crayfish get 3-4" but electric blues can get 6-8".
Known for carrying disease.
They also are great climbers , excape....

Grown somewhat attached ? If so may want to offer it a home of it's own to live out a full life / if a regular crayfish a 10 gallon tank is good. Even with your turtle never eating live food all it takes is once. Also turtle was there first , his home , may get territorial and hurt the crayfish ?

http://www.redearslider.com/prey.html

Tbh your turtle might get badly injured as well.