Optimizing paddy spacing for co-production: effects on rice-fish yields and soil-water quality in integrated farming systems

Integrated rice-fish farming (IRFF) is a promising agronomic strategy that enhances crop and fish productivity while improving soil health and resource use efficiency. This study aimed to assess the effects of different rice planting spacing on the growth and yield of rice and fish and evaluate soil fertility and water quality within an IRFF system. A field experiment was conducted using four (T1–T4) planting spacing; T1: 10 cm × 10 cm, T2: 15 cm × 15 cm, T3: 20 cm × 20 cm, and T4: 25 cm × 25 cm. Each treatment with three replicates was randomly allocated in a randomized complete block design. Growth and yield parameters of rice and fish were measured along with soil and water quality indices. Data were analyzed using ANOVA and Tukey’s test. Spacing influenced both rice and fish performance significantly. The 15×15 cm spacing provided the best balance, supporting high yields for both rice and fish without adverse effects on soil fertility or water quality. Narrower spacing enhanced total rice yield through higher plant density but reduced individual plant performance. Wider spacing improved individual plant growth yet lowered total yield. Soil nutrient levels (N, P, and K) and organic matter (OM) significantly increased across treatments, with T2 showing the highest enrichment. Water quality parameters (pH, EC, temperature, DO, NO3–, NH3) remained within non-toxic limits. This study suggests that 15×15 cm spacing optimizes rice-fish yields and enhances soil quality without compromising water quality in IRFF systems.