ISOLATION AND IDENTIFICATION OF BACTERIA ASSOCIATED WITH SPOILAGE OF RETAILED FISH (TRACHURUS TRACHURUS) (KOTE) IN ABEOKUTA

Fish is a good source of animal protein, but remains susceptible to microbial contamination and spoilage during storage, handling, and distribution. The aim of the study was to isolate and identify spoilage-associated bacteria from Trachurus trachurus (Kote) fish samples sold within selected markets in Abeokuta, Ogun State, Nigeria. Fish samples were collected from Lafenwa and Panseke, Abeokuta. The fish were stored and the microbial analyses were done on the tail, gill and mid-section for three days. The isolated bacteria were characterised using morphological, biochemical and molecular methods. The results showed that on Day 1, bacterial counts ranged from 1.225 × 10⁶ to 1.43 × 10⁷ cfu/g. By Day 2, most midsection and gill samples recorded values too numerous to count (TNC). This trend persisted on Day 3, except for the gill section from Panseke (3.52 × 10⁷ cfu/g) and the tail from Lafenwa (1.80 × 10⁷ cfu/g). Across all days, gill and midsection samples consistently showed higher bacterial loads than tail sections. Microbial succession revealed Staphylococcus spp. as the most persistent organism across all days, with increasing frequency from Day 1 (40.0%) to Day 3 (54.3%). Pseudomonas spp. also increased markedly (43.3%) on Day 3. In contrast, organisms such as Bacillus, Streptobacillus, Listeria, and Salmonella spp. declined or disappeared over time. Molecular identification of one isolate, initially presumed to be Staphylococcus, confirmed it as Providencia stuartii strain CUAB-FBSA. The study recommends strict hygiene in handling, maintenance of continuous freezing conditions, and routine microbial testing to control spoilage and improve food safety.