This study aims to determine the effect of Jatropha Curcas L. leaf extract on the freshness quality of Layang Fish (Decapterus sp.) At room temperature storage. The research consisted of two stages, namely preliminary research and main research. Preliminary research is determining the concentration of castor leaves. The main research is the concentration of Jatropha leaves used, which is 16% with a storage time of 10 hours, 14 hours, 18 hours and 22 hours. The test was carried out organoleptically (hedonic quality) and TPC. This design uses kruskall wallis for organoleptic data (hedonic quality), CRD to obtain TPC results. Organoleptic data and TPC that had a significant effect were tested by Duncan's continued test. The results showed that the fresh fly fish preserved with 16% castor leaf extract was able to maintain the quality of the fresh fly fish for 14 hours of storage. The chemical test results showed that the fresh fly fish with 16% castor leaf extract in 14 hours of storage, the microbiological quality obtained ALT value of 5.03 CFU / g, this fulfills SNI 2729.2013 concerning fresh fish.