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¹ Department of Marine Science, Faculty of Fisheries and Marine Sciences, Diponegoro University, Semarang, Central Java 50241, Indonesia
² Department of Aquatic Resources, Faculty of Fisheries and Marine Sciences, Diponegoro University, Semarang, Central Java 50241,
³ Study Program of Fisheries and Marine Technology and Business, Faculty of Fisheries and Marine Sciences, Diponegoro University, Teluk DOI : 10.4194/AQUAST3100 Viewed : 83 - Downloaded : 72 The Pacific white shrimp (Litopenaeus vannamei) is a globally important aquaculture species due to its rapid growth and broad environmental adaptability. In Indonesian coastal pond systems, frequent salinity fluctuations caused by tidal flooding (“rob”) engender unstable culture conditions that impair immunity and growth performance. This study evaluated the impact of mechanical filtration on water quality, growth and immune-related gene expression in L. vannamei under a low-salinity regime (10 ppt). A completely randomized design was used with semi-mass circular tanks (3 m diameter, 1 m depth, 5-ton capacity) operated either with or without mechanical filters (two replicates per treatment). All shrimp were fed a basal diet supplemented with 2 g kg⁻¹ alginate as an immunostimulant. Over a 20-day period (DOC 30, 40 50), water parameters (nitrite, nitrate, pH, turbidity) and expression of LGBP, ProPO, IGF- 2, HSP70, and MnSOD genes were assessed. Filtration significantly improved water clarity and stability (turbidity <187.75±28.69 NTU vs. 643.49±46.80 NTU in non-filtered systems), and reduced nitrite/nitrate accumulations (0.5 & 10 mg L⁻¹ vs. 5.0&50 mg L⁻¹). pH remained stable (7.7–8.0). Shrimp in filtered tanks reached higher final body weight (7.51±0.25 g) than those in non-filtered tanks (6.04±0.07 g). Gene expression results showed up-regulation of LGBP, ProPO, IGF-2, and HSP70 in filtered- treatment shrimp, while MnSOD was elevated in non-filtered shrimp, indicating higher oxidative stress. These findings demonstrate that the inclusion of a simple mechanical filtration unit in low-salinity recirculating systems enhances water quality, promotes growth, and improves immune homeostasis in L. vannamei under environmental stress. Keywords : Mechanical filtration Litopenaeus vannamei Low salinity Water quality Immune gene expression