Effects of Stocking Density on Fish and Rice Yields in Semi-intensive Rice-fish Culture of Climbing Perch (Anabas testudineus) in Rain-fed Rice Paddies

Abstract

We investigated the feasibility of culturing air-breathing carnivorous fish, climbing perch (Anabas testudineus), in a semi-intensive rice-fish system in Northeast Thailand. Fingerlings of two initial size classes (ca. 1 and 6 g per fish) were reared for 2.5 or 3.5 months to evaluate the effects of stocking density (0–80 fish∙m⁻²) on fish growth, fish yield, and rice yield. Fish reached market size (100 mm total length and 20 g wet weight) at all stocking densities. Total fish yield increased proportionally with stocking density, at least up to 60 fish∙m⁻², yielding 1.8–2.0 kg∙m⁻², indicating that climbing perch did not experience density-related constraints within this range. Trade-off existed between fish and rice yields, with rice yield declining significantly at stocking densities of ≥20 fish∙m⁻² (mean: 200 g∙m⁻²) compared to the no-fish control and 10 fish∙m⁻² treatments (mean: 520 g∙m⁻²). Fish revenue was comparable to, or slightly lower than, the combined costs of fingerling purchase and feed under concurrent culture conditions, with fingerling costs accounting for nearly 40% of this production cost. Overall, this study demonstrates that semi-intensive rice-fish culture of climbing perch is feasible in terms of fish production; however, further optimization of culture conditions is necessary to sustain both fish and rice yields at higher stocking densities. Specifically, extending the culture duration and/or improving fish growth performance are necessary to enhance profitability.