Histamine fish poisoning (HFP) is a major illness occurring throughout the world due to the consumption of quality of deteriorated fish containing pre-formed histamine from bacterial activities. In the study reported here, the histamine-producing bacteria were isolated from the muscle, gills and the gut of 19 samples of Indian mackerel (Rastrelliger kanagurta) from Mumbai, India. The isolates from modified Niven’s medium (MNM) were confirmed for their ability to produce histamine by using 4 different pH-indicator media, followed by HPLC analyses. Out of 202 isolates, 63 isolates produced considerable amounts of histamine on at least 3 out of 4 media used in this study. The histamine formers were identified by biochemical tests followed by sequencing of their 16SrDNA gene, which showed that 89% of the isolates belonged to 13 different genera of the family Enterobacteriaceae. The non-enterobacterial histamine-producing bacteria belonged to the genera Staphylococcus, Alkaligenes, Shewanella and Psychrobacter.