## 1 Introduction  
Aquaculture is a primary source of aquatic products for humans and represents the fastest-growing sector in the global farmed food industry, with total production nearly tripling over the past twenty years. However, high aquafeed production costs--accounting for 50-70% of total expenses--pose a significant bottleneck to the expansion of aquaculture [1, 2]. Microalgae have emerged as a valuable biological resource, showing a marked increase in application within the food and aquafeed markets over the past decade [3]. Their remarkable photosynthetic efficiency, rapid growth rates, and capacity for nitrogen and phosphorus assimilation from aquatic environments [4, 5], combined with their superior yields of carbohydrates, proteins, and lipids per unit area compared to other crops [6, 7], make them a promising solution for addressing food security and sustainability challenges [8]. As a result, enhancing microalgae cultivation techniques has become a critical priority. Electric stimulation has recently been explored as a novel technique to enhance microalgae growth and biomass production. For instance, [PERSON] et al. demonstrated that pulsed electric field (PEF) treatment could increase microalgae biomass by 10-20% [9]. Similarly, [PERSON] et al. achieved a 28.8% increase in lipid production and observed a morphological shift from cylindrical to spherical cells in _Acutodesmus dimorphus_ using a low-energy pulsed electric field (LE-PEF) [10]. Direct current (DC) electric fields have also shown promising results; [PERSON] et al. reported a doubling of triglyceride yield in _Chlorella_ sp. KR-1 with varying voltage intensities, although cell size initially increased and then decreased with higher voltages [11]. [PERSON] et al. found that continuous DC stimulation increased starch production in _Euglena gracilis_ by approximately 2.5 times, with increased cell volume due to suppressed division [12]. Furthermore, [PERSON] et al. observed that DC stimulation not only fostered the growth of _Scenedesmus obliquus_, with cell density increasing by a maximum of 13.1% and biomass by a maximum of 30.1%, but also notably improved its nutrient assimilation from water, particularly in terms of total phosphorus (TP) removal, which could achieve a maximum efficiency of 95.3% [13; 14]. [PERSON] et al. 's study on _Haematococcus pluvialis_ demonstrated that a 1 min direct current (DC) stimulation could increase cell density by 1.2 times [15]. This finding supports the effectiveness of DC stimulation as an approach to promoting microalgae growth, with advantages such as simple setup and lower energy requirements compared to pulsed electric fields. Despite these advances, most studies have been limited to small-scale cultivation, and the applicability of electric stimulation in large-scale production remains underexplored. _Nitzschia closterium_ f. _minutissima_ [PERSON] & Nelson, a marine eukaryotic unicellular diatom, is rich in proteins, carbohydrates, and other essential nutrients, making it a critical feedstock in marine aquaculture with considerable market potential [16; 17; 18]. While the large-scale cultivation of this diatom using photobioreactors has been investigated, there remains substantial room for improvement in the cultivation process [19]. Moreover, the potential for electric fields to enhance the growth of marine diatoms has yet to be explored in the existing literature. This study aims to determine if DC stimulation can improve the growth of _N. closterium_ f. _minutissima_ by investigating optimal conditions for promoting marine microalgae growth through electric stimulation. We will evaluate the effects of both brief and continuous DC stimulation at various voltages on growth dynamics, biomass accumulation, nutritional value, and cellular morphology and behavior.