| | Re: raising edible shrimp or crawfish?
I'm pretty sure the shrimp that are normally eaten & served in restaurants are a saltwater species, not a freshwater. No idea what they would need as far as tank size, etc.
As for crayfish, I know one of the most commonly eaten species in Louisiana is Procambarus clarkii, which is also one of the most commonly kept aquarium species. So it would definitely be possible. To raise them in significant quantities you would need a really huge tank though, as they can get somewhat large (up to around 5-6" I think) and crayfish will cannibalize each other during molts if there are not a lot of hiding spaces.