The invention relates to a device, a system and a method for grading live aquatic organisms in fluid into batches by using a central control system (7) that controls the grading process in a continuous manner resulting in optimisation of the grading process, said control system (7) optimizing individual grading components, namely concentration control (3) of fish, pump (4) speed and grader (5) settings, based on a software and a database (8) containing pre-set counting data.
