Sediments as Hotspots for Bacteria and Bacteriophages in Freshwater Fish Ponds in Lapai, Niger State, Nigeria

Bacteriophages are key regulators of bacterial populations in aquatic ecosystems and are increasingly recognized for their potential application as biocontrol agents in aquaculture. This study investigated the occurrence, distribution, and preliminary characterization of bacteriophages in freshwater fish ponds in Lapai, Niger State, Nigeria. Water and sediment samples were collected from two semi-urban aquaculture sites (Daudu Maza Road and Federal Low-Cost) and analyzed for bacterial loads and phage presence. Bacterial enumeration on selective media revealed significantly higher counts of Pseudomonas spp. and Escherichia coli in sediments compared to surface water, with the highest loads recorded in Federal Low-Cost Pond sediments. Bacteriophages were isolated using enrichment and double-layer agar techniques with Pseudomonas spp. and E. coli as host bacteria. Lytic phages were predominantly associated with Pseudomonas spp., exhibiting higher titers in sediment samples (up to 4.6 × 10sup6/sup PFU gsup-1/sup), whereas E. coli-specific phages were detected only at low abundance in one water sample. Distinct plaque morphologies suggested potential diversity among the isolated phages. The results demonstrate that fish pond sediments serve as critical reservoirs for both bacteria and bacteriophages, with phage distribution closely reflecting host availability. This study provides baseline data on bacteriophage occurrence in Nigerian aquaculture systems and highlights their ecological relevance and potential role in sustainable pathogen management as alternatives to antibiotics.