Well marmorkrebs are perfect candidates for you. Easy to breed, easy to be take care of, you can easily replace them and you can order them from websites.Everything is still in works. I don't have a solid project that I'm sure on yet, so I don't know what I'll need to have to work with. I'm simply at a brainstorming step still. I can't really plan until I have a set idea to go off of.
It's easy to screw up the project with sensitive fish species and it's most likely a really short project in this case. He needs a long term project. Also....the winter is coming up and you won't able to find them if you are focus on wild caught natives or not enough of them for your project.try sensitive fish species i guess, and change environmental factors