From The Stargate Omnipedia
Aris Boch's race
A species human in appearance, but with a unique physiology that prevents them from becoming host
symbiotes. This presented the race with a distinct edge over the Goa'uld. But when the parasitic species learned of it they forced Aris Boch's race into subordination, and conceived the drug Roshnah
. The entire race is addicted to the drug, which they must ingest on a regular basis in order to survive.
Aris Boch is hopeful that an antidote to the drug will be discovered, and gave Samantha Carter a sample for her to study in the hopes that one day his people may be freed from their subservience.
FIRST APPEARED: Deadman Switch
Deadman Switch - SG-1 encounters Aris Boch, a bounty hunter from a species that is physiologically unable to be used as Goa'uld hosts.