This study aims to test the influence of size grading on self-feeding behaviour, socialstructure (measured by the percentage of triggering acts per individual), growthperformances, and blood physiological variables of individually passive integratedtransponder (PIT)-tagged sea bass juveniles, using a computerized on-demand feeding systemcoupled with a PIT tag monitoring device. Three consecutive periods of 27 days each werecompared: a first period (P1) before grading (6 tanks of 100 fish; 40.2 ±  8.9 g) followed by a second period (P2) after grading. The protocolapplied aimed to create two groups of fish of similar mean weight but with either a low ora high coefficient of variation of weight(CVw) corresponding to an imposeddifference in social disruption (Tlow:CVw ~ 10%, 3 tanks of 60 fish each withsocial disruption;Thigh:CVw ~20%,3 tanks of 60 fish each, without social disruption). Tlow andThigh groups were studied over P2, and anadditional 27-day period under identical conditions (P3). The gradingprotocol used and/or time modified the social structure when comparing P1and P2. Thereafter, during P2 and P3,no difference could be observed in growth performances, feed demand, or physiologicalvariables between Tlow andThighgroups. Feeding rhythms and social structures weresimilar in both groups. In conclusion, such grading practice only transiently modifiesfeed demand behaviour and social structure built around the self-feeder, without furtherimprovement in individual growth performances in sea bass.