Effects of Density on the Growth Performance of and the Soil Microbial Communities Within a Rice-Frog-Loach Integrated Aquaculture System.

This investigation examines the influence of density on the growth performance of . and the structural and functional dynamics of paddy soil microbial communities within a rice-frog-loach integrated aquaculture system. Field experiments were conducted with five density gradients of (0.5, 1.0, 1.5, 2.0, and 2.5 × 10 individuals/667 m), designated as RFLS0.5, RFLS1.0, RFLS1.5, RFLS2.0, and RFLS2.5, respectively. Control treatments included rice monoculture (RM) and rice-frog co-culture (RFS). These findings demonstrated that as the density of loach increased, the weight gain ratio of showed a unimodal pattern, reaching its peak in RFLS1. Metagenomic analysis on paddy soil revealed that the RFLS1 facilitated the enrichment of nitrogen-fixing bacteria (), while concurrently suppressing proliferation of the potential pathogen and microbial markers in metal-contaminated environments of . Further, functional profiling indicated that RFLS1 group reached a peak activity in amino acid metabolism (14.52 ± 0.09%) and carbohydrate metabolism (14.44 ± 0.06%) and showed a higher proportion of glycosyltransferase (GT) abundance (41.93 ± 0.02%) than other groups. In summary, the optimal stocking density of in rice-frog-loach integrated systems was determined to be 1.0 × 10 individuals/667 m. This density not only promotes the growth of but also improves the structure of paddy soil microbial communities.