Dissolved oxygen (DO) management is a primary challenge in intensive aquaculture, where conventional aeration often suffers from high energy costs and low efficiency in decentralized systems. Oxygen transfer kinetics were investigated under oxygen-depleted conditions (initial DO = 2.4 mg L⁻¹) using the dynamic method. The system's performance was characterized through the volumetric mass transfer coefficient (kLa), Specific Oxygen Transfer Efficiency (SOTE), and dimensionless analysis (Reynolds, Schmidt, and Sherwood numbers). After 1 hour of operation, the DO concentration increased to 6.2 mg L⁻¹, achieving a net oxygen transfer of 9.55 ± 0.46 g. The system yielded a kLa of 1.44 h⁻¹ (R² = 0.97) and a SOTE of 76.4 ± 7.8 gO₂ kWh⁻¹. Dimensionless analysis (Re ≈ 2 x 10⁴, Sc ≈ 500, Sh ≈ 682) confirms that oxygen transfer is governed by hydrodynamic-induced interfacial area generation rather than molecular diffusion. Biological validation demonstrated that fish (catfish) grown under nanobubble-assisted conditions achieved a 43% higher growth rate over 17 days compared to non-assisted groups. These findings demonstrate that hydrodynamically controlled nanobubble spray systems provide an energy-efficient and scalable solution for decentralized aquaculture aeration.

Oxygen transfer enhancement in aquaculture was investigated using a low-cost fine-bubble spray system operated under controlled hydrodynamic conditions. Experiments were conducted under oxygen-depleted conditions (initial DO = 2.4 mg L⁻¹), and oxygen transfer kinetics were evaluated using the dynamic method. The dissolved oxygen concentration increased to 6.2 mg L⁻¹ within 1 h, corresponding to a net oxygen transfer of 9.55 ± 0.46 g. The volumetric mass transfer coefficient (kLa) was determined to be 1.44 h⁻¹ (R² = 0.97), while the specific oxygen transfer efficiency (SOTE) reached 76.4 ± 7.8 gO₂ kWh⁻¹. Dimensionless analysis (Re ≈ 2 × 10⁴, Sc ≈ 500, Sh ≈ 682) indicates a turbulent, convection-dominated transport regime. Biological observations showed a 43% increase in fish growth under spray-assisted conditions, indicating improved oxygen availability. The observed oxygen transfer enhancement was primarily associated with hydrodynamic interfacial area generation rather than diffusion-limited transport. The low-power configuration and simplified system design suggest potential applicability for decentralized aquaculture operations. The proposed approach also provides an engineering framework for evaluating low-cost aeration technologies under aquaculture operating conditions.