Won't hurt your other fish, correct.
I wonder what is producing gas inside the fish or what organ can produce the gas. Maybe in the event one of your guy's fish doesn't live, you could freeze it and then cut it open. The reason I say freeze it is if the fish isn't frozen and you cut it open then the gas will leave and that area will collapse, but if it is frozen then hopefully the bulged area would stay bulged allowing you to identify where the gas is accumulating.
I wonder what is producing gas inside the fish or what organ can produce the gas. Maybe in the event one of your guy's fish doesn't live, you could freeze it and then cut it open. The reason I say freeze it is if the fish isn't frozen and you cut it open then the gas will leave and that area will collapse, but if it is frozen then hopefully the bulged area would stay bulged allowing you to identify where the gas is accumulating.