As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT 5039, DURING PRE-FLIGHT CREW NOTICED AN ODOR OF FISHY ODOR W APU BLEED ON. CORRECTIVE ACTION: ISLOATE FAULT TO APU. C/W ISLOATE AND APU REPAIR JC 4900-2001. FOUND NO CONTAMINATION OR LEAKS IN APU COMPARTMENT. LEVEL A DECONTAMINATION OF ECS ACCOMPLISHED. C/W JC 2100-2007. NO ODOR PRESENT IN CABIN. (LP 9738626)