Aims This study investigated the tetracycline resistance potential of heterotrophic bacteria isolated from twenty-four freshwater fin-fish culture ponds in Andhra Pradesh, India. Methods and results A total of 261 tetracycline resistant bacteria (tetR) were recovered from pond water, pond sediment, fish gills, fish intestine and fish feed. Bacteria with high tetracycline resistance (tetHR) (n = 30) that were resistant to tetracycline concentrations above 128 μg mL−1 were predominantly Lactococcus garvieae followed by Enterobacter spp., Lactococcus lactis, Enterobacter hormaechei, Staphylococcus arlettae, Streptococcus lutetiensis, Staphylococcus spp., Brevundimonas faecalis, Exiguobacterium profundum, Lysinibacillus spp., Stutzerimonas stutzeri, Enterobacter cloacae and Lactococcus taiwanensis. Resistance to 1024 μg mL−1 of tetracycline was observed in Lactococcus garvieae, Staphylococcus arlettae, Enterobacter spp., Brevundimonas faecalis. Tet(A) (67%) was the predominant resistance gene in tetHR followed by tet(L), tet(S), tet(K) and tet(M). At similar concentrations of exposure, tetracycline procured at the farm level (69.5% potency) exhibited lower inhibition against tetHR bacteria compared to pure tetracycline (99% potency). The tetHR bacteria showed higher cross-resistance to furazolidone (100%) followed by co-trimoxazole (47.5%) and enrofloxacin (11%). Conclusions The maximum threshold of tetracycline resistance at 1024 μg mL−1 was observed in Staphylococcus arlettae, Enterobacter spp., Brevundimonas faecalis, and Lactococcus garvieae and tet(A) was the major determinant found in this study.

Ninety‐five Escherichia coli isolates recovered from different supply points of freshwater fish namely fish pond (W1, n = 16), wholesale fish market (W2, n = 14), retail fish market (R1, n = 29), street fish vending unit (R2, n = 30), and modern fish vending unit (R3, n = 6) were investigated for antimicrobial‐resistant profile and prevalence of antibiotic‐resistant genes. Overall, multidrug‐resistant (MDR) E. coli in the fish supply chain was 21% with higher MDR incidence in the downstream fish supply points. MDR was relatively higher in the tertiary fish supply points viz., retail fish market (45%), street fish vending unit (30%), and modern fish vending unit (15%) compared to the secondary fish supply point, that is, wholesale fish market (5%) and primary fish supply point, that is, fish pond (5%). All the ampicillin‐resistant isolates carried ampC gene, whereas only 21% of the β‐lactam resistant isolates carried blaCTX‐M‐gp1. The tetracycline resistance determinant, tetA (89%) was predominant in the tetracycline‐resistant isolates compared to tetB and tetD (11%). The trimethoprim resistance gene, dfrA and sulfonamide‐resistance gene, Sul1 were detected in 9% of the trimethoprim‐resistant isolates and 9% of the sulfonamide‐resistant isolates, respectively. Enterobacterial repetitive intergeneric consensus‐PCR has delineated the MDR isolates from the different fish supply points into three major clusters but all the MDR isolates from the street fish vending point are grouped into a single cluster. The results indicate an increase in the proportion of MDR E. coli and the occurrence of diverse MDR profiles in the downstream points of the fish supply chain that needs to be addressed to avoid fish‐food‐borne antimicrobial resistance.