The formation of algal detrital particles in a completely cell-detached form, namely, single cell detritus (SCD) was reported for the first time by the author during the microbial degradation process of macroalgal thalli. SCD display 3 characteristics suitable for feed for aquatic hatchery animals: 1) The size of SCD is in the 2-14 μm range, which is similar to that of dietary phytoplankton; 2) The cell wall components of SCD are partially degraded which facilitates digestion; 3) Bacterial cells are attached to SCD, which modifies the algal detritus to protein-rich particles. The use of SCD as a potential hatchery diet instead of phytoplankton culture, which is labor-intensive, was successfully demonstrated based on feeding experiments with Artemia. Further modification of SCD could include the attachement of bacteria to SCD which would exert beneficial effects on the hatchery animals. Use of SCD diets in fish feeding regimes is an attempt to introduce the concept of detrital food web to aquaculture systems, which could contribute to the development of sustainable fish nursery systems.