With the rapid development of intensive aquaculture， especially in recirculating aquaculture systems （RAS）， the efficient management of solid waste in aquaculture water has become a critical challenge. In RAS， the removal efficiency of suspended solids not only directly determines system performance but also affects its long-term operational stability. As the primary source of solid waste in aquaculture water， the characteristics of fish faeces are key prerequisites for achieving efficient water recycling. Moreover， excessive accumulation of faeces can directly damage fish gill and epidermal health， while also exacerbating microbial competition， promoting abnormal accumulation of nutrients such as ammonia and reactive phosphorus， and triggering water eutrophication and ecosystem dysfunction. This review systematically showed the latest researches on the characteristics of farmed fish faeces， influencing factors， and nutritional regulation strategies. Studies reveal significant interspecific differences in the physical characteristics of fish faeces， such as water stability， settling velocity， and particle morphology， which are jointly regulated by rearing conditions and feed composition. Although the chemical composition of feces is homologous to feed， there are notable differences in nutrient content， with the high enrichment of nitrogen and phosphorus being the primary contributors to water pollution. Regarding nutritional regulation strategies， feed optimization serves as the core approach for source control. This includes： （1） Improving nutrient digestibility by adjusting feed formulations and supplementing exogenous enzymes such as proteases and phytases； （2） Optimizing fecal physical properties using binders and buoyancy regulators； （3） Modulating gut health with probiotics and functional oligosaccharides to indirectly improve fecal composition. Despite current progress， further research is needed to address the specific requirements of different aquaculture systems and species. This review aims to provide a systematic theoretical foundation for innovative feed technology development and promote the green， sustainable advancement of the aquaculture industry.