Microbiological study of Sciaenid species collected from coastal waters of Niger Delta, Nigeria

Microbial load in Sciaenid fishes (Pseudotholithus. typus, P. senegalensis, and P. elongtatus) collected from the coastal waters in Rivers State, Nigeria were compared. Fish samples were purchased from local fishermen and transported in ice packs to the microbiology laboratory. The mean bacterial counts on the skin of the three fish species using nutrient agar for general purposes showed that P. typus had the highest loads (2.560 x 10³ CFU g^-1) followed by P. elongtatus with 1.360 x 10³ CFU g^-1 and P. senegalensis (8.00 x 10² CFU g^-1). Mannitol Salt Agar (MSA) used for the isolation and identification of Staphylococcus aureus revealed that P. senegalensis had 3.0 X 10^-1 CFU g-1, and Staphylococcus aureus was detected on the skin of P. typus and P. elongtatus. On SSA agar, the bacterial counts for the species were highest in P. senegalensis (6.326 x 10² CFU g^-1), followed by P. elongtatus and P. typus, with mean values of 5.90 x 10² CFU g^-1 and 5.350 x 10² CFU g-¹ respectively. Bacterial counts on TCBS were highest in P. senegalensis with a mean value of 3.15 x 10²10¹ CFU g^-1_, P. typus had 2.925 x 10² CFU g^-1 and P. elongtatus had 2.26 x 10² CFU g^-1. Fungi isolated on TCBS were low in all three fish species, with the highest mean value of 1.60 x 10¹ CFU g^-1 recorded on P. typus, followed by P. elongtatus (1.50 x 10¹ CFU g^-1) and P. senegalensis (1.25 x 10¹ CFU g^-1). The prevalent bacteria species in this study were Shigella, Aeromonas, Pseudomonas flourescens, Vibrio, Staphylococcus, Salmonella, Bacillus, and Micrococcus. Fungal counts found on the skin of the three fish species include Aspergillus flavus, Aspergillus niger, and Rhizopus stolonifera. All these organisms isolated in this study are of public health significance, and their presence suggests that foodborne illness could arise if these fish are consumed in an undercooked state.